Outlook Classic not opening properly or recording sent mails after 2026-01 Security Update (KB5074109) (26200.7623)

Chris Seagrave 345

Hi,

I installed in the Windows Security update (KB5074109) (26200.7623) on 14th January 2026 and following this update Outlook Classic has a couple of problems.

The first is that when I first start my laptop Outlook Classic opens, but when I close it down I am now unable able to open it again as Office tells me it is still open. I can go into Task Manager and close the Background Process relating to Outlook Classic which allows me to open Outlook Classic again, but this is not ideal as I would rather not do this. Alternatively I can restart my laptop and Outlook Classic will open, but if I close it down it won't re-open unless I either close the Outlook Background Process in Task Manager or restart the laptop.

The second issue is that I can send an email and it will be sent to the person I am sending the email to, but it doesn't show as being sent in the Sent Items folder, this is very strange, receiving emails is fine so far.

I have encountered this using a Yahoo Pop account, so I need some guidance on what I can do to resolve these issues in Outlook Classic?

Is there a specific fix in Outlook Classic or do I need to uninstall this (KB5074109) (26200.7623) update?

I can't seem to find a way of uninstalling update (KB5074109) (26200.7623), so may need some guidance here?

Many Thanks,

Chris

Locked Question. You can vote on whether it's helpful, but you can't add comments or replies or follow the question.

Gabe Bratton 686 Reputation points Microsoft Employee Moderator

2026-01-14T21:23:56.4333333+00:00

This issue is fixed with Windows out of band KB KB5078127.

Windows guidance, https://learn.microsoft.com/en-us/windows/release-health/status-windows-11-25h2#2738msg

Outlook guidance, https://support.microsoft.com/en-us/office/classic-outlook-profiles-with-pop-accounts-and-psts-hang-after-windows-updates-on-january-13-2026-590fe356-ecc2-49f4-b9e3-bd39fafa58f6
Bigbruva 155 Reputation points

2026-01-15T00:10:13.1533333+00:00

I am seeing the same issue following this security update and we are only using POP/SMTP accounts no IMAP. Security Update 2026-01 has caused this issue!
MUB 90 Reputation points

2026-01-15T02:56:29.68+00:00

Same problem, persistent with (KB5074109) (26200.7623) and cant uninstall. Following this. Also outlook seems to hang randomly with this update. Tried the suggestion of a handful of folks to reinstall the suite and no dice. Still hangs and freezes.
John W 315 Reputation points

2026-01-15T03:24:51.0166667+00:00

Outlook classic is completely unusable since this forced windows update. Random hangs, not saving emails, etc.

Hours of troubleshooting to no avail. Need a fix ASAP as it is disrupting business!!!
John W 315 Reputation points

2026-01-15T03:35:47.4233333+00:00

Uninstalling the update KB5074109 fixed it for me! I am now able to close outlook gracefully, reopen it, and all of my progress is saved. Fingers crossed no hangs.
Mirka Breen 55 Reputation points

2026-01-15T05:16:14.7133333+00:00

Same problem as the OP and no way to uninstall the troubling update 😢, Microsoft, PLEASE FIX THIS
Chris Seagrave 345 Reputation points

2026-01-15T12:08:24.2633333+00:00
Update on 15-01-2026, I went through a lot of the suggestions and I couldn't fix it, I also couldn't uninstall either.

I went to my local computer repair shop and I showed them this thread and explained my problems with Outlook Classic after the 2026-01 Security Update (KB5074109) (26200.7623). I also mentioned that my wife also uses the same laptop with her own Microsoft Account and her Outlook Classic was working ok, we both use POP accounts, I have Yahoo POP and she has Gmail POP, the repair guy said that Microsoft may have tested Outlook and Gmail accounts which were fine and not bothered to test for Yahoo POP accounts hence my issue.

His suggestion to me was to do a System Restore, which I have carried out for no cost this morning, the restore point had been automatically been set on 13th January before the 2026-01 Security Update (KB5074109) (26200.7623) had been done, so I am now back to having a setup before Tuesdays Windows Update and I have also paused the Windows Update so 2026-01 Security Update (KB5074109) (26200.7623) doesn't re-install for the time being.

The outcome is that Outlook Classic opens pulls email through and closes properly as the restore has rolled back 2026-01 Security Update (KB5074109) (26200.7623).

I did have to repair and reinstall a couple of apps, notably OneDrive, but that is working ok now.

To access System restore:

Go to Start and type restore

Select "Create a restore point"

System Properties window opens > select System Restore

Follow the prompts to select time stamped restore point

Confirm you want to restore using selected restore point

Laptop reboots and restores, ensure laptop is plugged in as it takes about 30 mins to do

I will be monitoring Outlook Classic to see if it keeps working and fingers crossed Microsoft sort out this issue before the next Windows Update next month.
John W 315 Reputation points

2026-01-15T14:03:18.98+00:00

So some users don't have the update listed at the bottom of Windows Update -> Update History -> Uninstall Updates?

It was listed there for me and I was able to uninstall it without issue.
Jim Cofer 25 Reputation points

2026-01-15T16:42:37.93+00:00

I had the same issue: Outlook Classic 64-bit started hanging\freezing on Tuesday after installing KB5074109. I tried every obvious fix: M365 Quick Repair, M365 Online Repair, the PST repair tool (which errored out), a new Outlook profile... nothing seemed to help other than uninstalling KB5074109. I'm coming up on 24 hours without KB5074109 and no Outlook issues.

Note that the same Outlook install also had a work profile to a M365 server, and that had no issues.
Jim Cofer 25 Reputation points

2026-01-15T16:45:31.8666667+00:00

PS - if you try uninstalling KB5074109 and get an error message, uninstall Windows Sandbox THEN try uninstalling the update. Worked for me!
Joe Kirchgessner 50 Reputation points

2026-01-15T18:02:13.19+00:00

Same with me, classic MS Outlook opens just once after boot. If classic MS Outlook is closed, it will not reopen. When forcing a Restart, Outlook is a task that will not close automatically. Forcing Outlook to close in the Task Manager works, but all changes made in Outlook are forgotten, it opens up and repops all messages. Very frustrating!!!!!!!!!!
Gabe Bratton 686 Reputation points Microsoft Employee Moderator

2026-01-15T18:08:09.93+00:00
Editing to note that pausing OneDrive, disabling OneDrive, unlinking OneDrive did not mitigate the issue. The only two workarounds I know of currently are:

Remove KB5074109

Move PSTs outside of the OneDrive folder (complicated to do and not a reasonable workaround in most cases).
Joe Kirchgessner 50 Reputation points

2026-01-15T18:18:28.77+00:00

I just uninstalled KB5074109 and Outlook is working perfectly. Gabe, Sorry, I saw your note too late to attempt it but it feels like, as you said, Outlook was not closing correctly as it was a very persistent task when doing a reboot (ie it would not close).
GFL4 75 Reputation points

2026-01-15T21:46:14.8666667+00:00

I have the same problem. Plus every time I open outlook it redownloads all my emails. I can only send simple emails with no attachments, no forward, no reply and no manual send/receive. Only closes normally when there is a hang and I indicate to not wait for outlook to respond. Otherwise need to end process in task manager. This is for classic outlook 2024. Also no way to undo KB5074109 in update history. Queried chatgpt and advice is to wait for the fix. Use webmail for heavy tasks. Also advice is not to leave outlook running if not in use because of corruption risk of PST files. But the more users that complain, the more likely Microsoft will address.
GFL4 75 Reputation points

2026-01-15T21:55:38.2333333+00:00

It looks like this has been flagged on Microsoft known issues page. Workaround is to use webmail.
AlistairJT 25 Reputation points

2026-01-15T22:03:58.52+00:00

I had 2 days of trying to live off my phone with 80+ emails a day coming in and Outlook freezing and then reverting back to old PST file.

I have now uninstalled the 14th Jan patch and Outlook working fine again.
Gabe Bratton 686 Reputation points Microsoft Employee Moderator

2026-01-15T22:07:21.38+00:00

We posted a Known Issue article to acknowledge the issue, https://support.microsoft.com/en-us/office/classic-outlook-pop-account-profiles-hang-and-freeze-after-windows-11-update-to-kb5074109-590fe356-ecc2-49f4-b9e3-bd39fafa58f6. The Outlook and Windows Teams are currently investigating. I'll share more as soon as there are updates to share.
Mirka Breen 55 Reputation points

2026-01-15T22:13:45.97+00:00

I was able to UNINSTALL by ignoring the standard advice to go through Settings and instead went to Control Panel, then to Programs, then on the left side find updates and open them and voila: the option to UNINSTALL was there for the least three updates. Uninstalled the Jan 13 offender, and all is working again. Curiously, I see a new installed update from today. But so far, Outlook Classic has recovered, fingers crossed.
Ian 30 Reputation points

2026-01-15T22:46:48.42+00:00

I have spent several hours trying to fix this issue and , after uninstalling KB5074109 all is back to normal. Microsoft has wasted thousands if not millions of hours of their customers' time by not thoroughly testing their security update.
Jamie 0 Reputation points

2026-01-16T10:47:37.7066667+00:00

I removed "Package_for_RollupFix~31bf3856ad364e35~amd64~~26100.7623.1.20" via the command prompt and this resolved the issue.
alison snowdon 0 Reputation points

2026-01-16T13:46:10.6266667+00:00

Ive tried everything!! How do I do the unistall? Uninstalling KB5074109 worked for us on several PCs
Hornblower409 7,005 Reputation points

2026-01-16T14:23:51.51+00:00

@alison snowdon said

How do I do the unistall?

Please review the Answers and comments in this thread. There have been multiple suggestions on how to uninstall KB5074109.

Hornblower409 Answer on Jan 14, 2026, 11:07 PM

How to uninstall KB5074109

AlistairJT and John W

Windows Update -> Update History -> Uninstall Updates. It was listed there for me and I was able to uninstall it without issue.

Mirka Breen

Control Panel, then to Programs, then on the left side find updates

Chris Seagrave

do a System Restore .. the restore point had been automatically been set on 13th January before the 2026-01 Security Update (KB5074109)
Anonymous

2026-01-16T15:48:38.64+00:00

Fix this, Microsoft! This is far more than a minor inconvenience!
Jay Emerson 5 Reputation points

2026-01-16T15:54:45.79+00:00

Now it won't even open. The first symptoms were 'hanging when moving an email from Inbox to a subfolder'. Now I can't get in. Test your code. Don't make us test your code.
SR 55 Reputation points

2026-01-16T16:20:35.9+00:00

Does anyone know a solution for users who do not have the option to "uninstall" the update? It's not showing as an uninstall selection for us - please see screenshot below. Webmail isn't really a functional workaround for our operation.

What is the investigation status Microsoft?? Being on day 2 of this mess is unacceptable - we cannot run our business like this.
Ray Garofalo 5 Reputation points

2026-01-16T17:33:14.6566667+00:00
I'm having the same issues discussed in this thread.

I'm also having these additional hanging & freezing issues (Win 11 Pro w Outlook Classic (365)):

When attempting to copy messages from any account to a .pst data file, Outlook immediately freezes.

On several occasions, despite killing Outlook via Task Manager, I've had to restart Windows to restart Outlook.

Will update further if any additional issues arise.
Ed Lyons 15 Reputation points

2026-01-16T17:56:25.0166667+00:00

Had all the problems noted in above comments, plus several others (e.g. Task snoozes and changes did not take). Just uninstalled KB507419 from both my desktop and my wife's laptop (both are POP), and both of our Outlooks are functioning again. However, now that I have turned off Automatic Updates to prevent re-installation of faulty Update, how am I going to know when its repaired replacement is available?
Mirka Breen 55 Reputation points

2026-01-16T18:28:03.4366667+00:00

Like you, I will NOT allow automatic updates until I am certain this is tested and fully repaired. Functional email is not a little thing, trivial thing, or optional. It is the number one most pivotal use of computers for most people.

If I were Microsoft (HEH!) I would uninstall this for everyone everywhere and only return with a different version of this update when fully tested and in no way crippling to email, no matter which kind you have from all the Microsoft products.

To think they did this to their own product, still used by millions.

I hope someone will put an update or a link to an official statement from Microsoft regarding a fix done.
SR 55 Reputation points

2026-01-16T20:41:05.7866667+00:00

PLEASE RESPOND MICROSOFT! What is the timeline for this to be fixed?? It's been over 2 business days since your forced update has caused our email system to completely fail. We CANNOT uninstall the update - it's not an option on our control panel. This is a nightmare for small business owners!

Does anyone know how to uninstall the update when it isn't showing as an option to uninstall. I am clearly not an IT professional.
GFL4 75 Reputation points

2026-01-16T20:51:08.64+00:00

Maybe they could give us a rollback update until resolved
GFL4 75 Reputation points

2026-01-16T20:56:17.5966667+00:00

And only use outlook lightly or not at all because of pst corruption risk. And dont leave outlook running or idle. Make sure shut down in task mgr.
Hornblower409 7,005 Reputation points

2026-01-16T21:02:05.8966667+00:00

@Ed Lyons said

how am I going to know when its repaired replacement is available?

Monitor this Support Notice.

Classic Outlook POP account profiles hang and freeze after Windows 11 update to KB5074109

https://support.microsoft.com/en-us/office/classic-outlook-pop-account-profiles-hang-and-freeze-after-windows-11-update-to-kb5074109-590fe356-ecc2-49f4-b9e3-bd39fafa58f6
Jim Cofer 25 Reputation points

2026-01-16T21:04:26.98+00:00

SR - For goodness sake... calm down! People in this thread have listed multiple ways to uninstall the update, from the Settings app to System Restore to PowerShell. Have you tried all of those options first?
GFL4 75 Reputation points

2026-01-16T21:15:57.07+00:00

I am not an advanced user and after checking chatgpt for risk using dism or winRE is not viable for users line us.
SR 55 Reputation points

2026-01-16T21:21:12.18+00:00

Jim Cofer - "for goodness sake", read what I wrote above. My system does NOT give me the option to uninstall. See screenshot. Try running your business without email for 2 days and see how calm you would be going into the weekend without any timeline of a fix. Regards.
Todd Whitelow 10 Reputation points

2026-01-16T21:53:52.74+00:00

Hello,

I wanted to share my recent experience in case it helps others. After installing the Windows security update KB5074109 (January 2026), Outlook Classic began to hang and would not properly close profiles, which prevented reopening and caused lingering processes in the background. Additionally, emails marked for deletion would not sync properly, and emails reappeared upon reopening Outlook.

To mitigate the issue, I uninstalled the KB5074109 update, which resolved the Hang and sync problems, allowing Outlook to function normally again. I also paused Windows updates for two weeks while awaiting an official fix from Microsoft, as suggested by support threads and community discussions.

We are eager to see if Microsoft releases an update to resolve these issues while maintaining device security up to date. Looking forward to hearing about the next update, and I would be very interested in hearing about any other workarounds or solutions that others have found.

Thanks!
Susan Belmonte 0 Reputation points

2026-01-16T22:09:11.8533333+00:00

Experiencing identical problem. Spent >4 hours with Best Buy Geek Squad, to no avail. Found this chain of comments and tried to uninstall KB5074109 (which was also installed on my PC 01/14/2026), but it is not listed as being a recent update. Instead it indicates 2 updates for today (01/16/2026) - KB5066128 and KB5054156... which was likely done by the Geek Squad folks when they took over my PC. Afraid to delete them, as I haven't seen any one else reference these updates. Also, where do you find updates from past days (vs. today only)?
Gabe Bratton 686 Reputation points Microsoft Employee Moderator

2026-01-16T22:39:21.5733333+00:00
Hi all,

The Windows Team is still investigating the issue. There is no fix ETA yet. I want to share a learning and ask if anyone could test my finding.

In one of the In App support tickets one customer found that if they move the PSTs outside of OneDrive that mitigated it for them. It's a lot of work to move the PSTs so not something I would want everyone to do.

--
Editing to note that pausing OneDrive, disabling OneDrive, unlinking OneDrive did not mitigate the issue. The only two workarounds I know of currently are:

Remove KB5074109

Move PSTs outside of the OneDrive folder (complicated to do and not a reasonable workaround in most cases).
Jim Cofer 25 Reputation points

2026-01-16T23:04:04.8166667+00:00

SR - use the Control Panel, PowerShell or System Restore. If none of those THREE OPTIONS work for you, come back. This isn't rocket surgery.
Jim Cofer 25 Reputation points

2026-01-16T23:08:10.66+00:00

That would be typical Microsoft. The Office team puts PSTs in your Documents folder by default, but the OneDrive team can't be bothered to support PSTs, so you get a permanent error message in OneDrive. Terrific. I'm not doing any of that, but let us now when a proper fix comes.
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Hornblower409 7,005 Reputation points

2026-01-17T02:59:43.2766667+00:00

@Gabe Bratton said

one customer found that if they move the PSTs outside of OneDrive that mitigated it for them. If anyone can test this, please share if helped.

Gabe

My test setup:

Windows 25H2 (OS Build 26200.7623)
Outlook Classic 365 MSO (Version 2512 Build 16.0.19530.20144) 64-bit
Existing MS 365 Business Standard account.
Added a Gmail POP account.
The PST for the POP account is in OneDrive\Documents\Outlook Files
OneDrive Sync is active.

I can't get Outlook to fail.
Is there something else I can do that might force a failure?
A Snowdon 0 Reputation points

2026-01-17T12:11:18.56+00:00

I found the 4109 update easily in the 'recent update' list so deleted it, rebooted and everything went back to normal. Created a new .pst file just in case but probably not necessary.
Jamie Stephenson 0 Reputation points

2026-01-17T18:25:15.1833333+00:00

** Be patient **
The uninstall paused for a long time but finally processed. The subsequent reboot also paused for a long time on 100% but finally rebooted. Just go get coffee/lunch at each stage and let the "MS magic" happen.
Oh, it did then work.
All I want to do now is work out how to relocate the files from the cloud to the PC as I tried that and send/receive stopped again.
Joanne Cohen 10 Reputation points

2026-01-17T19:49:45.09+00:00

having the same problem, Outlook doesn't save mail, changes and stops responding.
KK 0 Reputation points

2026-01-17T20:03:09.16+00:00
I had the same issue. I googled it and see if there's any update online. Thank God!

Google AI gave me a few suggestions and I followed one of the suggestions to repair Microsoft 365 and it worked for me. the first suggestion worked and I didn't have to proceed to 2. or 3.

Fixes for "Classic" Outlook 365

Repair Office/365 Programs: Go to the Control Panel > Programs and Features, right-click "Microsoft 365", and choose Change > Online Repair.

Run ScanPST (Inbox Repair Tool): If the application opens but fails, your data file may be corrupted. Run the scanpst.exe tool to repair the .pst or .ost file.

Create a New Profile: Go to Control Panel > Mail > Show Profiles > Add to create a new, clean profile.
Jay Korobow 25 Reputation points

2026-01-17T20:14:00.88+00:00

I have confirmed KB5074109 is still gone for me after MS Tech via remote access successfully removed it with DISM (other tries all failed.) Despite reinstalling WIN11 and OFFICE and various repairs and turning off acceleration and more stuff, the problems persist: intermittent at times and brickwall-stoppage at times. Can get freeze/not-responding opening an email, selecting reply, switching from inbox to sentfiles, launching outlook/can freeze on loading profile, etc. ETC. I do not have OneDrive on. I do not do automatic updates: i allowed this one manually because it kept aggressively pestering me. The MS Tech somehow wiped out all earlier system restore points when he made new one before he worked remotely on my pc. Things were normal for a few minutes after the uninstall/removal (enough minimal testing he went on his way with my thanks) but then the issues came back, in some case more fiercely. That happened earlier after reinstalls or running repairs... a few good moments of use then NAHHH. Hope this helps anyone researching, looking for ideas or news! TY
Linda Speicher 5 Reputation points

2026-01-17T20:14:04.3766667+00:00

I'm not sure whether I turned Sandbox on or off - I went to optional features in settings and checked the box next to Windows Sandbox and then rebooted and now my Outlook appears to be working fine. Only time will tell.

I guess we are all going to have to migrate to Windows 365, but I'm just not ready for that, since I am going to have to hire somebody to come help me set it up. I have my own domain where my email "resides" and I can use Webmail to look at it, but I want it to download off of there into Outlook. Hoping to get through tax season before I have to make this change.
Jay Korobow 25 Reputation points

2026-01-17T20:26:08.0566667+00:00

sorry i cannot figure how to put comments in certain places or how to view most recent comments. doing my best. I just posted an update and forgot to add... ai suggested this be tried:

Run SCANPST.EXE (Inbox Repair Tool) on your PST files. However others caution leave outlook off corruption may worsen. so, any helpful advice? Here's my earlier update 3PM EST Jan 17 for convenience:

I have confirmed KB5074109 is still gone for me after MS Tech via remote access successfully removed it with DISM (other tries all failed.) Despite reinstalling WIN11 and OFFICE and various repairs and turning off acceleration and more stuff, the problems persist: intermittent at times and brickwall-stoppage at times. Can get freeze/not-responding opening an email, selecting reply, switching from inbox to sentfiles, launching outlook/can freeze on loading profile, etc. ETC. I do not have OneDrive on. I do not do automatic updates: i allowed this one manually because it kept aggressively pestering me. The MS Tech somehow wiped out all earlier system restore points when he made new one before he worked remotely on my pc. Things were normal for a few minutes after the uninstall/removal (enough minimal testing he went on his way with my thanks) but then the issues came back, in some case more fiercely. That happened earlier after reinstalls or running repairs... a few good moments of use then NAHHH. Hope this helps anyone researching, looking for ideas or news! TY
Joanne Cohen 10 Reputation points

2026-01-17T22:05:59.8633333+00:00

I used the uninstall in the Settings as suggested to remove the January 13th security update. My email is working again.
Jay Korobow 25 Reputation points

2026-01-17T22:46:35.76+00:00

i earlier commented on my dysfunctional Outlook POP scenario (after removal/uninstall of KB5074109 a few ok tests then returned to havoc, again, as it did after repairs reinstalls etc) that i do not have OneDrive active/running. well: i used GROK to ascertain that ->who told me no blue cloud icon, and go to search OneDrive and get a screen that says SIGN ON: means its not running! I reported that as some say may be related to the "havoc". Well, now I am potentially running SCANPST per GROK and i noted in prep work in TASK MGR an occurrence of process OneDrive... GROK says oh well maybe it is running after all some auto thing. So sorry for misreporting, wish there were a way to trust Ai and merge with expert suggestion here and post timely comments and so on, oh i wish i wish. TY
Chris Maher 0 Reputation points

2026-01-17T23:56:13.62+00:00

Uninstalling the 2026-01 Security Update (KB5074109) (26200.7623) worked - HOWEVER, even though I clicked for them not to update automatically, it updates every freaking morning, so I have to uninstall it every day!
Jay Korobow 25 Reputation points

2026-01-18T06:15:47.26+00:00

I apologize ...while getting more conversant in this technical arena (and here) I find it challenging to know where to comment (and to easily find where the most recent comments are) especially as I am one of those users whose KB5074109 was successfully removed/uninstalled by an MS Tech using DISM (other attempts all failed) and stayed removed! -yet the Outlook randomized havoc... numerous tasks freeze and hang or give unusual results DESPITE the removal and reinstalling WINDOWS and OFFICE and running repairs and more. I know it worked for others and it even worked for me for a short time (minutes!) One objective is why others stay recovered yet me and many do not. I looked into the OneDrive thing (as a contributing factor to those still adrift) at first I thought (and reported) it OFF/gone but turns out it has a mind of its own and sneaks back on and tries to synchronize and more and may indeed may still be an explanatory contributing factor. I also have large volume of saved messages (files in search folders) I use as archive and searching them (and indexing to assist that) has always been a bit kludgy or problematic for me. That could explain differences in resolution for some as well. In fact, a coordinated test (with GROK) shows I endtask many things suspected of being involved and launch Outlook via Profile Selection always in SAFE mode now (where less havoc generally occurs)...and i can select Inbox, open and view a New message, hit reply, enter some text (If i say YES to show pics it FREEZES on SEND in all modes!) and SEND = ALL OK. I can go to FILE pulldown to EXIT (or go to options....) and all is well as long as I do it quickly. If i wait a minute or 2 just choosing FILE it freezes and stalls (but not if I do it sooner) and requires aborting Outlook for recovery. Coordinated tests involve watching what pops up in Task Manager, as I wait/IDLE, and the pop-up that appears to generate this particular issue is WINDOWS SEARCH INDEXER... after about a minute it comes on EVEN THOUGH I have UNCHECKED OUTLOOK from the Index Searching Dialog! (for all my recent tests.) Once he appears FILE and other tasks will hang and freeze or misbehave! It would be nice if MS techs read this (thread/etc) or advanced users that could absorb and communicate the effects (of my testing or outcomes) to folks in a position to resolve. The MS Tech that removed KB give me a ticket to follow-up but when i finally reached someone (with great diffculty) to report Oh sorry it was only fixed/resolved for a couple of minutes then NO... 3 days ago she says yeah we are working on it go check the updates... sent me an email with a link to an internal site that aborted when i tried. So I came here where helpful smart people abound but no one really has a clue (sorry) or addresses my wordy verbose reports or seems to CARE> Gotta be a BETTER WAY!
Jay Korobow 25 Reputation points

2026-01-18T06:22:11.3666667+00:00

for above, confirmation from GROK after many hours of testing: Yes—your test nailed the resurfacing culprit exactly: Windows Search Indexer popping up after just ~1 minute of idle time, immediately leading to the File pull-down freeze/not-responding. This confirms our suspicion—the delay allows the indexer to activate (even with Outlook unchecked in Indexing Options), and it conflicts with UI actions like menu access by probing your large PST archives in the background. The quick test pre-wait worked because it happened before the resurfacing; the idle buildup triggers the stall. This is a common post-KB5074109 residual (Microsoft's investigation updated January 15, 2026, still ongoing—no full patch yet), where indexing resumes asynchronously on idle, amplifying hangs in setups with massive email volumes like yours.
Bernadette M 0 Reputation points

2026-01-18T08:12:02.1633333+00:00

Had the same problem. Very frustrating, spent hours trying to fix problem on laptop, found it was also happening on pc, so checked online for issues found this discussion.

Uninstalling the KB5074109 update worked, but I had to shut down and then reboot for the fix to take effect. Restarting to complete the uninstall process alone wasn't enough to prompt Outlook to work again for my POP/SMTP email account.

Like others, I've now paused updates, which is never ideal. But getting work related emails is more important.
Hornblower409 7,005 Reputation points

2026-01-18T13:12:37.1866667+00:00

@Chris Maher said

I clicked for them not to update automatically, [but] it updates every freaking morning

I believe that you have to Pause Updates. If you do it right you should see a "Updates paused until ..." banner.
Wendy Shoffit 10 Reputation points

2026-01-18T20:44:48.7166667+00:00

OMG... thank you for the solution! After uninstalling the Security Update, my Outlook seems to be working just fine. I was going nuts with resetting, uninstalling, reinstalling, etc. So thankful to know it wasn't something I did and it wasn't something permanently broken.

Wendy
Gabe Bratton 686 Reputation points Microsoft Employee Moderator

2026-01-18T22:31:41.4833333+00:00
@Hornblower409 ,

Make sure you have KB5074109 installed (just double checking you did not already remove it). To repro you could add another PST in the same OneDrive folder or add another POP account to the profile. If you add another PST test dragging some email to it. With two POP accounts test sending email from each one to the other. In both cases Outlook should go to Not Responding pretty quickly.

From my testing this issue only happens when the PSTs are in the OneDrive folder.

Editing to note that pausing OneDrive, disabling OneDrive, unlinking OneDrive did not mitigate the issue. The only two workarounds I know of currently are:

Remove KB5074109

Move PSTs outside of the OneDrive folder (complicated to do and not a reasonable workaround in most cases).
Kysa351 0 Reputation points

2026-01-18T23:46:37.59+00:00

I have uninstalled the update and outlook is working again now so I hope they fix as I use a pop account outlook classic with windows 11
Theresa Adams 0 Reputation points

2026-01-19T00:47:14.7266667+00:00

How do you keep it from re-installing. My settings say no automatic updates, yet it re-installed the day after I uninstalled it.
Hornblower409 7,005 Reputation points

2026-01-19T01:02:40.78+00:00

@Gabe Bratton said

Make sure you have KB5074109 installed

Package_for_RollupFix~31bf3856ad364e35~amd64~~26100.7623.1.20 | Installed | 2026-01-15 15:38

add another POP account to the profile

Done. Now have 1 MS365 Business Standard, two GMail as POP.

the PSTs are in the OneDrive folder

dragging some email to it. sending email from each one to the other

No failures. (I'm cursed?).

It may require more traffic than I'm generating just testing? But I don't have any high volume accounts I can configure as POP.

GMail POP is not one that it picks on?
Hornblower409 7,005 Reputation points

2026-01-19T01:05:15.6633333+00:00

@Theresa Adams said

How do you keep it from re-installing. My settings say no automatic updates, yet it re-installed the day after I uninstalled it.

Try Pause Windows Updates as well as no automatic updates.

https://support.microsoft.com/en-us/windows/pause-updates-in-windows-643e9ea7-3cf6-7da6-a25c-95d4f7f099fe
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Michael McCarter 5 Reputation points

2026-01-19T14:33:33.9066667+00:00

Any update from the MS engineering team on when a new update will come out to fix this issue with MS Outlook Classic?

Any update would be greatly appreciated to all of us with this issue.

Thank you.
Gabe Bratton 686 Reputation points Microsoft Employee Moderator

2026-01-19T15:15:11.93+00:00
Thanks for testing @Jay Korobow

I tested further and verified your findings. Pausing OneDrive, disabling OneDrive, unlinking OneDrive did not mitigate the issue. The only two workarounds I know of currently are:

Remove KB5074109

Move PSTs outside of the OneDrive folder (complicated to do and not a reasonable workaround in most cases.)

The Windows Team is still investigating the issue. If anyone cannot get the update removed please use WebMail until we either find a simpler workaround or a fix is available. As soon as we get anymore information I will add it to the Known Issue and post back here, https://support.microsoft.com/en-us/office/classic-outlook-pop-account-profiles-hang-and-freeze-after-windows-11-update-to-kb5074109-590fe356-ecc2-49f4-b9e3-bd39fafa58f6.
Hornblower409 7,005 Reputation points

2026-01-19T16:01:44.36+00:00

@Theresa Adams said

How do you keep it from re-installing. My settings say no automatic updates, yet it re-installed the day after I uninstalled it.

You have to Pause Windows Updates as well as no automatic updates.

https://support.microsoft.com/en-us/windows/pause-updates-in-windows-643e9ea7-3cf6-7da6-a25c-95d4f7f099fe
Hornblower409 7,005 Reputation points

2026-01-19T16:09:16.1066667+00:00

@Gabe Bratton said

Move PSTs outside of the OneDrive folder

I finally got my Outlook to hang. After a reboot I quit OneDrive and ran ScanPST on my PSTs. It failed on both of my POP PSTs and on a non-POP PST in my OneDrive folder with the error:

But, if I Cut/Paste the PSTs out of the OneDrive folder to anyplace else then ScanPST completes the Repairs. I can then Cut/Paste the PSTs back into the OneDrive folder and ScanPST can still complete the scan (no error found).

I have no idea what this implies.
Jay Korobow 25 Reputation points

2026-01-19T17:00:52.5666667+00:00

Ty ty Gabe for all you do and reply. I actually got a full scan pst to repair clean yet also still outlook random havoc. Even safe mode, one drive and indexing and more disable or isolated. Next will try small pst test profile acct. If any news of import will post here. Bless u.
Barb6110 0 Reputation points

2026-01-19T20:09:59.0933333+00:00

I am unable to uninstall update KB5074109 as it is not listed on the uninstall options list. I'm having issues moving emails to folders - especially those stored on my computer. It freezes the program & I have to shut it down through task manager. Earlier today it also froze all outgoing mail. The only way I could send mail was by logging on to the website. It didn't matter whether I was using a gmail account which downloads into Outlook or my Outlook email address.

As John W indicated above, we need a fix ASAP. It is disrupting business.
Hornblower409 7,005 Reputation points

2026-01-19T21:14:58.3666667+00:00

@Barb6110 and @Robert P said

I am unable to uninstall update KB5074109 as it is not listed on the uninstall options list.

Please review the Answers and comments in this thread. There have been multiple suggestions on how to uninstall KB5074109.

Hornblower409's Answer on Jan 14, 2026, 11:07 PM
How to uninstall KB5074109

AlistairJT and John W
Windows Update -> Update History -> Uninstall Updates. It was listed there for me and I was able to uninstall it without issue.

Mirka Breen
Control Panel, then to Programs, then on the left side find updates

Chris Seagrave
do a System Restore .. the restore point had been automatically been set on 13th January before the 2026-01 Security Update (KB5074109)

Then Pause Windows Updates as well. You should see an "Updates paused until ..." banner.

https://support.microsoft.com/en-us/windows/pause-updates-in-windows-643e9ea7-3cf6-7da6-a25c-95d4f7f099fe
Jay Korobow 25 Reputation points

2026-01-19T23:18:18.9666667+00:00

One recent comment suggested the culprit update has many effects, and a system restore or a working uninstall perhaps fully undoes lingering culprits so some fully recover. For me (and an MS Tech remotely accessing) classic removal failed and failed and they did DISM... which likely did not UNDO EVERYTHING. Unfortunately the MS Tech also permanently removed earlier restore points in their efforts for me. It also seems to matter what Outlook activity (tasks, syncs, etc) went on while bad stuff (culprits) was still there. So Joe may be ok but Susie not OK, now, as we see: lingering secondary damage (profile/PST corruption or incomplete SSU rollback) rather than the kernel APIs still being broken. WHAT A MESS!
GFL4 75 Reputation points

2026-01-19T23:57:59.3+00:00

Bear with me as i am not an advanced user. Under word it shows that there is an office update on 1/13. I dont know if this is a separate update or part of the offending kb update. How about if microsoft tests first and if it finds it to be the cause then rolls back just the office part of the kb update. Another idea is if the updated outlook is the culprit they could make a previous version for us to reinstall. Just thinking.
Hornblower409 7,005 Reputation points

2026-01-20T01:39:30.2333333+00:00

@GFL4 said

Word shows an office update on 1/13. I dont know if this is a separate update or part of the offending kb update.

My guess would be that this is KB5002829. Security update for Word 2016: January 13, 2026. Unrelated to KB5074109.
https://support.microsoft.com/en-us/topic/description-of-the-security-update-for-word-2016-january-13-2026-kb5002829-576f9f49-7914-486c-bb8c-0ef4ac1eaf3d

How about if microsoft tests first and if it finds it to be the cause then rolls back just the office part of the kb update

Since we still do not have a definitive answer from an official Microsoft source, it would be premature to speculate on possible fixes. Plus, the latest reports I have seen indicate that it might be an interaction with OneDrive and not a purely Outlook problem.
M G 0 Reputation points

2026-01-20T06:33:28.07+00:00

I have also wasted HOURS on this problem with the issues in Outlook, repairing and reinstalling Office, doing scanpst.exe runs, etc MULITPLE TIMES. I don't have the KB5074109 available in the uninstall updates list and even the DOS commands to remove it did not work! It is definately installed. For some reason, the only two restore points available on my restore option are after the date the update was installed??

Please please please give me other suggestions Microsoft?? This is urgent.
M G 0 Reputation points

2026-01-20T06:39:27.34+00:00

For @Hornblower409 and @Gabe Bratton my POP mail file is on OneDrive.
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Hornblower409 7,005 Reputation points

2026-01-20T07:09:30.48+00:00

M G said

the DOS commands to remove it did not work

Which commands did you try and what was the output or error message?
Hornblower409 7,005 Reputation points

2026-01-20T07:11:44.3233333+00:00

M G said

my POP mail file is on OneDrive

If you want try moving your PST files, instead of uninstalling KB5074109, please see my answer:

Hornblower409 Jan 19, 2026, 11:35 PM
https://learn.microsoft.com/en-us/answers/questions/5707915/outlook-classic-not-opening-properly-or-recording?page=3#answers
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Hornblower409 7,005 Reputation points

2026-01-20T07:17:43.1266667+00:00

MG said

It is definitely installed

Do you see it using any of these methods?

Command wmic qfe list

PowerShell Get-HotFix | Where-Object {$_.HotFixID -eq "KB5074109"}
dark-rider 60 Reputation points

2026-01-20T14:20:11.0933333+00:00

Dear Gabe,

for months, I try to report a bug with Outlook (classic) and Search Indexer, for example here and here, but until now, this bug was neither registered nor fixed.

Because some users mentioned Search Indexer to trigger Outlook hanging, could you also take the problems mentioned into considerance?
Gabe Bratton 686 Reputation points Microsoft Employee Moderator

2026-01-20T14:28:20.4433333+00:00

@dark-rider

I did more testing with Windows Search disabling it completely and this POP PST hang still occurred. The main factor is if the PST is in OneDrive. It also does not matter if OneDrive is stopped, the bug still occurs.

For the search issue you are seeing the best thing to do is to submit an In App ticket via Help, Contact Support. Contact Support is only available for Office Subscription.

For the POP Hang the Windows Team is working on a fix. I will get an update today and update the Known Issue with whatever guidance they provide, https://support.microsoft.com/en-us/office/classic-outlook-pop-account-profiles-hang-and-freeze-after-windows-11-update-to-kb5074109-590fe356-ecc2-49f4-b9e3-bd39fafa58f6.
dark-rider 60 Reputation points

2026-01-20T14:44:26.9633333+00:00

Dear Gabe,

thank you for your quick answer.

I can also confirm that for me storing my PST files only locally and not on OneDrive, I fortunately did not see the bug mentioned in this thread up to now.

But what I see is that auto-complete of e-mail addresses in Outlook is suddenly much slower than before for some days. Maybe there is a connection to the current bug?

For the search issue you are seeing the best thing to do is to submit an In App ticket via Help, Contact Support. Contact Support is only available for Office Subscription.

Among many other things, I also tried this - but also no response. Because the search indexer bug in Outlook (classic) with Windows 11 (not with 10) is not easy to observe, no one else seems to take care about the - only in background - caused massive CPU load and SSD wear. Maybe when you have the time you could try to reproduce it, I'd be very glad.
Fred 5 Reputation points

2026-01-20T15:53:40.9666667+00:00

Additionally to a freezing shoutdown of Outlook, I also experience a strange behaviour in my pop3 mail account. I have my mails organized in folders. If I move a mail to the designated folder, close outlook and re-open it (after shooting down the task in task manager), The mail is again in the inbox. The mails also don't get deleted from the mail server, once downloaded to Outlook.
GFL4 75 Reputation points

2026-01-20T15:58:27.4666667+00:00

Yep, all part of the original symptoms for me when this all started.
Bruniel de Menezes Machado 10 Reputation points

2026-01-20T17:16:37.3666667+00:00

Hello,

We are experiencing a similar scenario in our company, with more than 100 users impacted. The context is as follows:

The KB5074109 update is installed on part of the environment; however, we have also identified the same Outlook freezing and hanging issue on machines that do not have this KB installed.

We are currently working with a Microsoft engineer, who states that the root cause is related to the synchronization of PST files with OneDrive. According to him, when the PST files are removed from OneDrive and configured locally in Outlook, the issue no longer occurs. We performed this test and, in fact, Outlook stopped freezing and hanging.

We also identified that the OneDrive version installed in our environment is “Build 25.238.1204.0001 (64-bit)”. However, this version is not listed in the official OneDrive release notes, available at: https://support.microsoft.com/office/onedrive-release-notes-845dcf18-f921-435e-bf28-4e24b95e5fc0

According to the documentation, the latest published build is 25.222.1112.0002. Given this, we would like to know if anyone else is facing this issue and could check which OneDrive version is installed in their environment.

Is it possible that Microsoft has released a build with stability issues?

Finally, please note that our environment uses Microsoft 365 (Exchange Online).
Gabe Bratton 686 Reputation points Microsoft Employee Moderator

2026-01-20T17:37:46.64+00:00
@Bruniel de Menezes Machado The root cause of this issue is the Windows Update and is unrelated to the OneDrive version. We are updating the guidance for this issue here, https://support.microsoft.com/en-us/office/classic-outlook-pop-account-profiles-hang-and-freeze-after-windows-11-update-to-kb5074109-590fe356-ecc2-49f4-b9e3-bd39fafa58f6.

If you can use webmail please do. The only options otherwise are:

Move PSTs out of OneDrive, https://support.microsoft.com/office/how-to-remove-an-outlook-pst-data-file-from-onedrive-b6b9e522-59bd-40f7-949f-168d0aa9b38e.

Remove the Windows Update, How to uninstall a Windows Update - Microsoft Support.
Dieter Brinker 0 Reputation points

2026-01-20T17:46:48.27+00:00
Try the following steps:

Stop OneDrive if used

Close Outlook with Taskmanager

Copy the Outlook-PST-File to a new place

Use ScanPST.Exe (to find in Programs /Microsoft Office/root/Office16)

Repare Outlook-PST-File with ScanPST

Copy the repared file back to its original place

Start Outlook
Hornblower409 7,005 Reputation points

2026-01-20T17:51:18.1366667+00:00

[Removed by author]
Bruniel de Menezes Machado 10 Reputation points

2026-01-20T17:52:58.31+00:00

@Gabe Bratton But what explains the fact that machines which did not receive this update (KB5074109) are also experiencing the issue?
Hornblower409 7,005 Reputation points

2026-01-20T18:02:04.3866667+00:00

[Removed by author]
Gabe Bratton 686 Reputation points Microsoft Employee Moderator

2026-01-20T18:02:51.19+00:00
@Bruniel de Menezes Machado Please share the Windows version so I can check which you are on (right click Start, click Run, Type Winver, press OK).

So far we found the following platforms are affected:

Windows 11 25H2 KB5074109, Windows 11, version 25H2 update history - Microsoft Support

Windows 11 24H2 KB5074109, Windows 11, version 24H2 update history - Microsoft Support

Windows 10 22H2 KB5073724, Windows 10 update history - Microsoft Support
Bruniel de Menezes Machado 10 Reputation points

2026-01-20T18:10:59.6333333+00:00

@Gabe Bratton 23H2
Gabe Bratton 686 Reputation points Microsoft Employee Moderator

2026-01-20T18:51:16.33+00:00

@Bruniel de Menezes Machado I am checking with the Windows Team and will share back what they say. In my opinion since you have confirmed moving PSTs outside of OneDrive resolves the issue then I expect it's the same bug. It's the same January 13th update as the other platforms, January 13, 2026—KB5073455 (OS Build 22631.6491).
Michael Kloß 0 Reputation points

2026-01-20T19:02:19.2933333+00:00

Move PST-File from OneDrive to Localdrive seams to solve all my Problems. THANX !
Bruniel de Menezes Machado 10 Reputation points

2026-01-20T19:28:36.64+00:00

@Gabe Bratton We have some computers that did not receive the January patch, meaning they were not updated, yet they are still experiencing the issue. Coincidentally, OneDrive was automatically updated (as expected) and is now running version 25.238.1204.0001.

We attempted to roll back the OneDrive update, but without success. The issue persists, and an increasing number of users are being affected. We continue to move PST files out of OneDrive synchronization, but this is a time-consuming task.

Additionally, the Microsoft engineer assigned to the case is investigating the issue internally and will get back to us.
S P 0 Reputation points

2026-01-20T21:53:37.4833333+00:00

Genau das gleiche Problem. Zunächst dachte ich, dass der Grund für Einfrieren von Outlook das Löschen von vielen Mails auf dem Server gewesen wäre, weshalb die PST Datei neu angelegt werden müsste. Von dem Update hatte ich keine Ahnung. Deinstallation und Neuinstallation von Outlook oder MS Office brachte nichts. Fing immer wieder an einzufrieren. Auch KI wusste nicht was zu tun ist. Daher per Backup ein paar Tage zurück und es lief. Jetzt habe ich erstmal Updates für 4 Wochen ausgesetzt, da ich keine Zeit habe, hinterher wieder aufzuräumen. Es wird leider immer schlimmer.
M G 0 Reputation points

2026-01-20T22:33:36.4166667+00:00

@Hornblower409 I found it was there using this:

Package_for_RollupFix~31bf3856ad364e35~amd64~~26100.1742.1.10 | Staged | Security Update |

Package_for_RollupFix~31bf3856ad364e35~amd64~~26100.7623.1.20 | Installed | Security Update | 14/01/2026 5:26 PM

Then ran this, as suggested in the thread (for each version number):

C:\Windows\System32>dism /online /remove-package /PackageName:Package_for_RollupFix~31bf3856ad364e35~amd64~~26100.7623.1.20

Deployment Image Servicing and Management tool

Version: 10.0.26100.5074

Image Version: 10.0.26200.7623

Processing 1 of 1 - An error occurred - Package_for_RollupFix Error: 0x800f0825

Error: 0x800f0825

DISM failed. No operation was performed.

For more information, review the log file.

C:\Windows\System32>dism /online /remove-package /PackageName:Package_for_RollupFix~31bf3856ad364e35~amd64~~26100.7623.1.10

Deployment Image Servicing and Management tool

Version: 10.0.26100.5074

Image Version: 10.0.26200.7623

An error occurred trying to open - Package_for_RollupFix~31bf3856ad364e35~amd64~~26100.7623.1.10 Error: 0x800f0805

The specified package is not valid Windows package.

Error: 0x800f0805

The specified package is not valid Windows package.

The DISM log file can be found at C:\WINDOWS\Logs\DISM\dism.log
Hornblower409 7,005 Reputation points

2026-01-20T22:48:38.43+00:00

M G said

dism remove. An error occurred trying to open 0x800f0805

All I can suggest is to contact Microsoft Support. Your questions should be something like "Can not uninstall KB5074109"

MS 365 - User Support
https://www.microsoft.com/en-us/microsoft-365/support

Free Chat Support
https://support.microsoft.com/home/contact

And reference this Support article so they know what you are trying to fix.
https://support.microsoft.com/en-us/office/classic-outlook-pop-account-profiles-hang-and-freeze-after-windows-11-update-to-kb5074109-590fe356-ecc2-49f4-b9e3-bd39fafa58f6

Outlook doesn't stay open long enough without hanging to allow me to change any settings to point it somewhere else.

Not sure if it will help since you can't move your PST, but you can access your Outlook Profile settings via the Control Panel Mail app.

See "Update or change your email settings from Mail in Control Panel" in
https://support.microsoft.com/en-us/office/change-or-update-email-account-settings-in-outlook-for-windows-560a9065-3c3a-4ec5-a24f-cdb9a8d622a2
M G 0 Reputation points

2026-01-20T22:50:18.2466667+00:00
@Hornblower409 I used a different command suggested somewhere on here to see it was there, but it also shows if I use this one:

wmic qfe list

Caption CSName Description FixComments HotFixID InstallDate InstalledBy InstalledOn Name ServicePackInEffect Status

http://support.microsoft.com/?kbid=5067931 SHELLPC Update KB5067931 NT AUTHORITY\SYSTEM 10/29/2025

https://support.microsoft.com/help/5054156 SHELLPC Update KB5054156 NT AUTHORITY\SYSTEM 10/8/2025

https://support.microsoft.com/help/5074109 SHELLPC Security Update KB5074109 NT AUTHORITY\SYSTEM 1/14/2026

SHELLPC Update KB5071142 NT AUTHORITY\SYSTEM 12/2/2025
Hornblower409 7,005 Reputation points

2026-01-21T01:13:06.4333333+00:00

M G Said

I used a different command suggested somewhere on here to see it was there, but it also shows if I use this one: wmic qfe list

I don't doubt that you have KB5074109 installed. But if the dism /online /remove-package fails, then I don't know how to help you remove it. You will need Microsoft Support. (See my previous comment).
M G 0 Reputation points

2026-01-21T01:21:09.98+00:00

Thank you @Hornblower409 for your help. I will follow up further with MS as suggested.
Jay Korobow 25 Reputation points

2026-01-21T04:53:32.9866667+00:00

A new MS tech (the third via legit remote access) tried to address my Outlook POP3 mayhem yesterday and finally resorted to building a new OUTLOOK profile infrastructure which was then linked (to ISP) and populated (by exports and moves and sends) and has now been tested heartily for a full day. While not fast (indexing still off) not one freeze or mishap or error yet besides things like duplicate or missing emails from the NEW BUILD process inadequacies. You may recall KB5 could not be uninstalled fully on my setup so the LCU (partially at least i guess) was removed via DISM yet problems still persisted, even with other fixes and specials. I have asked GROK to corroborate and explain along the way, and asked for something to share with affected users that may help them (at least understand) Here it is: ->

Update on KB5074109 (KB5) Outlook POP3 Mayhem: After multiple MS tech sessions involving failed uninstall attempts from Update History (error 0x800f08xx series) and partial DISM removals (likely just the LCU, leaving SSU intact), my system still showed KB5 in history but with lingering freezes during Outlook repairs/exports. The breakthrough came from creating a fresh Outlook profile: Tech set it up cleanly with my ISP's POP3 settings, then we tediously exported/imported archives from the old corrupted profile (ignoring interim hangs). No clean backups meant some duplicates and unexpected undeletes from the server, but after a full day of medium testing in the new profile—no freezes at all, even with indexing disabled and OneDrive misbehaving. This suggests KB5 often corrupts the existing profile/PST infrastructure beyond reliable repair (ScanPST or /Repair fall short), but building a new one from scratch bypasses it effectively, importing data piecemeal without reintroducing issues.What it means for remediation: Partial DISM LCU removal might not fully revert KB5's damage (history lags, remnants persist), explaining why some full uninstalls via Settings recover better—though security risks make waiting for MS's patch wiser. If freezes persist post-new-profile, check for large imports or OneDrive sync as triggers. MS is investigating, but no fix yet (as of Jan 20, 2026); this workaround bought me stability without drastic steps. Hope this helps others—share your results!
S P 0 Reputation points

2026-01-21T14:31:20.04+00:00

Kann die Ursache bei mir gewesen sein. Da PST Dateien lokal viel Speicher brauchen, liegen die bei One Drive. Outlook ist eingefroren nach diesem Update. Nur: One Drive gehört ja wohl zur MS Umgebung. Bei Speicherung auf Google Drive hätte man das ja noch nachvollziehen können. Seltsam.
Hornblower409 7,005 Reputation points

2026-01-21T14:55:22.5433333+00:00

@S P said

Outlook froze after this update. But OneDrive is part of the Microsoft ecosystem ... Strange

It appears that the problem might be due to an unintended interaction between OneDrive and Outlook that only affects some Outlook Classic users with POP email accounts and PST files in the OneDrive directory.
MartMcd 2,555 Reputation points Volunteer Moderator

2026-01-21T18:25:32.87+00:00

Moderator note :-
Jay Korobow Your willingness to help in Microsoft Q&A is very much appreciated, however please refrain from simply copying and pasting AI generated content. Users are capable of asking GROK or other AI services themselves, most ask here because they want help from a real person, please continue to share your own experience with similar issue rather than what GROK says about it.

Please read AI Usage Policy as well at the Microsoft Q&A Code of Conduct.

Thank you,
Martin
be 5 Reputation points

2026-01-22T03:50:54.18+00:00

Hi, Does anyone know when there is going to be a solution to this? Removing a security update to make Outlook work is ridiculous and dangerous. I have also removed KB5074109 but it is trying to install again on windows update so I am just not rebooting. When is Microsoft going to roll out a fix for this?
Hornblower409 7,005 Reputation points

2026-01-22T04:17:05.22+00:00

@be said

when there is going to be a solution to this?

There is no final solution at this time. You can monitor the official Microsoft Support article on this issue for updates.

https://support.microsoft.com/en-us/office/classic-outlook-pop-account-profiles-hang-and-freeze-after-windows-11-update-to-kb5074109-590fe356-ecc2-49f4-b9e3-bd39fafa58f6

Removing a security update to make Outlook work is ridiculous and dangerous.

There is another approved workaround - Move any PST files out of your OneDrive folder and use ScanPST to check for errors.

Once you have moved all of your PSTs you can resume Windows Updates. KB5074109 won't break your Outlook.

To see the locations of your PST files:

From the Outlook menu do File > Account Settings > Account Settings. Select the "Data Files" tab.

If your Outlook is not useable - Open the Windows Control Panel. Click on the "Mail" link. On the "Mail Setup" dialog click "Data Files ..."

How to remove an Outlook .pst data file from OneDrive

https://support.microsoft.com/en-us/office/how-to-remove-an-outlook-pst-data-file-from-onedrive-b6b9e522-59bd-40f7-949f-168d0aa9b38e

ScanPST

https://learn.microsoft.com/en-us/troubleshoot/outlook/data-files/how-to-repair-personal-folder-file

removed KB5074109 but it is trying to install again on windows update

Pause Windows Updates
https://support.microsoft.com/en-us/windows/pause-updates-in-windows-643e9ea7-3cf6-7da6-a25c-95d4f7f099fe
Peter Marshall 5 Reputation points

2026-01-22T17:37:37.6866667+00:00

Is there any update on this fix? I have been without email for over a week as webmail only brings up my outlook email, not my ISP email. Very inconvenient.
Hornblower409 7,005 Reputation points

2026-01-22T18:02:24.5133333+00:00

@Peter Marshall said

Is there any update on this fix?

The latest information is always in this official Microsoft Support document.
https://support.microsoft.com/en-us/office/classic-outlook-pop-account-profiles-hang-and-freeze-after-windows-11-update-to-kb5074109-590fe356-ecc2-49f4-b9e3-bd39fafa58f6

At the moment there are two workarounds. No final resolution.

Workarounds - Doing either one should fix the issue:

1 -- Move any PST files out of your OneDrive folder and use ScanPST to check for errors.

How to remove an Outlook .pst data file from OneDrive
https://support.microsoft.com/en-us/office/how-to-remove-an-outlook-pst-data-file-from-onedrive-b6b9e522-59bd-40f7-949f-168d0aa9b38e

ScanPST
https://learn.microsoft.com/en-us/troubleshoot/outlook/data-files/how-to-repair-personal-folder-file

Once you have moved all of your PSTs you can resume Windows Updates. KB5074109 won't break your Outlook.

2 -- Uninstall the Jan 2026 Update KB5074109 and Pause Windows Updates.

How to uninstall a Windows Update
https://support.microsoft.com/en-us/windows/how-to-uninstall-a-windows-update-c77b8f9b-e4dc-4e9f-a803-fdec12e59fb0

Pause Windows Updates
https://support.microsoft.com/en-us/windows/pause-updates-in-windows-643e9ea7-3cf6-7da6-a25c-95d4f7f099fe

If you can not uninstall KB5074109 thru normal means contact Microsoft Support and ask "How to uninstall KB5074109?"
https://support.microsoft.com
nyjklein 50 Reputation points

2026-01-22T18:05:05.0766667+00:00

I've been having this problem also. I saw that one of the suggested workarounds is to move the pst file out of onedrive.

I'm thinking that if that's the primary driver behind this issue, wouldn't quitting onedrive before starting outlook also be a reasonable workaround?

(and of course restarting it after you've closed outlook)
Hornblower409 7,005 Reputation points

2026-01-22T18:11:51.3333333+00:00

@nyjklein said

wouldn't quitting onedrive before starting outlook also be a reasonable workaround

Give it a try. And please report back.

But the reports I have seen indicate that just having the PSTs in the OneDrive folder is enough to cause problems.

There are also many people who depend on OneDrive for other critical operations.
Peter Marshall 5 Reputation points

2026-01-22T18:28:08.6266667+00:00

Thanks but the windows update is not there for me to uninstall or I would have, trust me.

As for moving my PST file out of OneDrive, the steps seem fairly straight forward but at my age not sure I want to attempt. MS should be providing a fix to resolve since we all pay for o365. Am quite disappointed.
Hornblower409 7,005 Reputation points

2026-01-22T19:06:31.93+00:00

@Peter Marshall said

the windows update is not there for me to uninstall

It does not show up in normal Windows Updates for some people.

not sure I want to attempt

You should contact Microsoft Support and ask for assistance.

Open a browser to https://support.microsoft.com/en-us/home/contact
Tell us your problem -> "How to uninstall KB5074109" or "How to remove an Outlook .pst data file from OneDrive"
[Get Help], {Scroll down to the bottom of the page}, [Sign in to contact Support]
Sign in with any Microsoft account.
Products and services -> "Microsoft 365 and Office" -> "Outlook", [Confirm]
Choose a support option -> "Chat with a support agent in your web browser"

MS should be providing a fix to resolve

Microsoft is working on a final resolution for this issue. Until then the workarounds are all there is. You can check the current status of their progress in the official Support doc for this bug.

https://support.microsoft.com/en-us/office/classic-outlook-pop-account-profiles-hang-and-freeze-after-windows-11-update-to-kb5074109-590fe356-ecc2-49f4-b9e3-bd39fafa58f6
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be 5 Reputation points

2026-01-22T21:43:36.88+00:00

My pst is on Dropbox. That is how I keep my file backed up. I have been doing it that way for over 10 years. I hope Microsoft takes this issue seriously. I won't be moving my files off Dropbox and risk losing data.
Peter Marshall 5 Reputation points

2026-01-22T22:50:16+00:00

Unfortunately the last update is from early yesterday in link on their progress. Even an estimated timeline would be appreciated.
Hornblower409 7,005 Reputation points

2026-01-22T22:59:28.6133333+00:00

@be said

My pst is on Dropbox.

Are you seeing the same problems with Outlook as reported by OneDrive users?

I won't be moving my files off Dropbox and risk losing data.

If you are concerned about Microsoft's continued support for Outlook with a PST on Dropbox - I would suggest you use the "Ask a Question" button at the top of this page and start a new thread with that specific question.
Hornblower409 7,005 Reputation points

2026-01-23T00:30:31.31+00:00

@Peter Marshall said

the last update is from early yesterday .. Even an estimated timeline would be appreciated.

Any official updates will have to come from a Microsoft Employee.

This mention @Gabe Bratton to Gabe Bratton (the Microsoft Employee/Moderato) who has been monitoring this thread will notify him of your comment.
TamakoTakamatsu-6777 10 Reputation points

2026-01-23T01:33:25.6533333+00:00

Apologies if I'm posting in the wrong space. I just wanted to mention that I chatted with a person from MS Support yesterday, and he assured me that uninstalling KB5074109 and pausing automatic updates temporarily would not be dangerous for my pc--something that the "uninstalling option" warns against, and which filled a non-expert with me with great anxiety. This was therefore such a relief to hear. He said that if I'd been updating windows regularly (through automatic updates) and also had anti-virus software (I have Trend Micro), I should be fine until a fix was announced by MS.

I hate having to wait for a new security update that will fix this Outlook Classic problem, but at least a lot of the fear (that I was exposing my pc to danger) has gone away. Of course, I'm not an expert and perhaps others might want to chat with MS SUpport, too. Just wanted to share, though. Am very grateful for the conversations here!
Chris Maher 0 Reputation points

2026-01-23T03:10:58.2+00:00

thanks. that's what I'm doing and waiting for them to fix it.
Judy-3739 0 Reputation points

2026-01-23T04:44:04.1733333+00:00

And here I thought it was just me. I ended up buying a new laptop thinking it was a virus and two local IT technicians later, who couldn't tell me the issue, I finally get an answer from contact Microsoft Help. This was a very expensive bug Microsoft.
Jay Korobow 25 Reputation points

2026-01-23T08:31:40.96+00:00

A legit MS Tech remotely working on my problem rebuilt and populated a brand new classic Outlook POP3 profile to use. I have been testing it and fixing some stuff (missing this, dupes) for 3 days: good news: not one freeze or mishap! bad news: I notice its sending PST stuff to OneDrive still! (to C: Onedrive/desktop/local folder... ) i learned this is not desirable and asking for reoccur troubles. Seems OneDrive hijacks some desktop files (and other things.) i go to desktop where Tech made the local folder and its there but its path is C:OneDrive/Desktop/local... i learn many techs MISS this. there are ways to avoid this (not use desktop, etc) so I am fixing it. thought anyone seeking to set up without OneDrive should be made fully aware!
Hornblower409 7,005 Reputation points

2026-01-23T08:55:05.7866667+00:00

@Jay Korobow said

sending PST stuff to OneDrive still! (to C: Onedrive/desktop/local folder... )

That might be a local folder that MS created on your drive to store your PST files.

If you open your Windows Explorer (This PC), do you see a "OneDrive" link?

And if you open the OneDrive link you should see all the files in your OneDrive folder.

If you search thru the folders and files in your OneDrive folder, can you find the PST? If not, then it is a local folder. Even if it has "OneDrive" in the file name.
G Arthur 15 Reputation points

2026-01-23T11:58:51.7133333+00:00

After 4+ hrs with MS Tech Support update was removed and Windows 11 reinstalled but did not make any difference at all, problem still exists.

PLEASE NOTE the problem is NOT JUST with closing Outlook and not saving sent emails, NO CHANGES AT ALL ARE SAVED - if you move emails from inbox to folders, apply categories or flags, mark as read, create or delete calendar reminders, create new folders etc etc, absolutely nothing that you do is saved. Once you close and reopen Outlook EVERYTHING has reverted back to the state it was when the update was installed and all new emails since then are downloaded again. Have tried not closing Outlook to avoid this but it periodically crashes so you have to restart it and lose all the changes!

Using web mail instead is NOT an acceptable workaround as the lack of comparable features makes managing affairs effectively nigh impossible, let alone the nightmare of trying to transfer all changes back to Outlook once it is fixed as only the inbox will update automatically...
Hornblower409 7,005 Reputation points

2026-01-23T13:27:47.4733333+00:00

@G Arthur said

update was removed and Windows 11 reinstalled but did not make any difference at all, problem still exists

Have you tried the other suggested workaround?

Move any PST files out of your OneDrive folder and use ScanPST to check for errors.

How to remove an Outlook .pst data file from OneDrive
https://support.microsoft.com/en-us/office/how-to-remove-an-outlook-pst-data-file-from-onedrive-b6b9e522-59bd-40f7-949f-168d0aa9b38e

ScanPST
https://learn.microsoft.com/en-us/troubleshoot/outlook/data-files/how-to-repair-personal-folder-file

Once you have moved all of your PSTs you can resume Windows Updates. KB5074109 won't break your Outlook.
nyjklein 50 Reputation points

2026-01-23T15:18:22.8966667+00:00

Indeed. This possible workaround did not work for me.
ALICIA ELENA CURIEL CORDERO 10 Reputation points

2026-01-23T15:29:44.69+00:00

justr call me "crazy" but the weird thing is that if ypu try "NEW OUTLOOK" withouth the W11 UPDATE, it works. i'm not a fan of this new interface. you can open your PST files BUT you can only see the mails that are inside SUBFOLDERS, the emails inside the mail PST they don't show at all. so this "new outlook" is not a "real" solution and besides it lacks of several options to personalize the toolbar, no "developer", no no no. just bring back the "OUTLOOK CLASSIC", please.
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Hornblower409 7,005 Reputation points

2026-01-23T16:14:30.09+00:00

@ALICIA ELENA CURIEL CORDERO said

if you try "NEW OUTLOOK" ... it works

Yes. As far as I know, New Outlook for Windows is not affected by the KB5074109 bug.

BUT you can only see the mails that are inside SUBFOLDERS, the emails inside the mail PST they don't show at all

Not correct. New Outlook for Windows does have limited support for PST files. But you can not "attach" an existing PST file to a POP account in New Outlook for Windows. That limits the value of this to existing Classic Outlook users.

https://support.microsoft.com/en-us/office/open-and-find-items-in-an-outlook-data-file-pst-2e2b55a4-f681-4b93-90cb-31d39349fb95

You can move, copy, and delete emails and folders in your .pst file. You can also drag and drop emails between your mailbox and .pst files.

You could add your POP or IMAP account to New Outlook for Windows, which give you access to the mail currently on your email server, and open your PST files to be able to see your old mail.
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ALICIA ELENA CURIEL CORDERO 10 Reputation points

2026-01-23T16:26:32.8366667+00:00

that "limited support" is getting on my nerves, lol. anyway i need to be patient. i just fear that this "error update" is a "tricky" way to force us into migrate to the "new outlook" hoping i'm wrong lol
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GFL4 75 Reputation points

2026-01-24T02:01:30.35+00:00

For those of us who have not uninstalled and are waiting for microsoft to fix, what happens if another update is issued to fix some of the problems but not outlook classic problems. Should we pause all updates now until fixed. Will we still be able to uninstall problem update if kb5074109 is superceded but not fixed for classic outlook?
Hornblower409 7,005 Reputation points

2026-01-24T02:21:15.1833333+00:00

@GFL4 said

what happens if [Microsoft Update Maze]

Sorry. I can not answer anything about what Microsoft may or may not do. Use the "Ask a question" button at the top of this page to start a new thread or contact Microsoft Support.
Jay Korobow 25 Reputation points

2026-01-24T08:05:03.0533333+00:00

Thank you for kind advanced expert reply! What I was trying to convey is I originally thought creating a new folder directly on my visible desktop (the one I get when I show desktop or Win+D) would yield a plain boring normal local safe spot with no global cloud ties suitable for PST files to avoid any KB5 OneDrive Outlook mayhem – turned out FALSE for me. I have since learned that in most modern Windows 11 setups like mine with OneDrive known folder move enabled for Desktop that visible desktop surface is actually the redirected cloud-synced version living under OneDrive-Personal. Thus any folder I create there even if I name it something innocent like LOCALFOLDER or PST_SAFE ends up being cloud-bound with files subject to sync upload potential conflicts Files On-Demand interference and the usual PST corruption risks being popularly discussed. My initial assumption that plain old desktop equals automatically safe local was incorrect and the existence of OneDrive in some longer paths I saw for my Outlook data files was indeed a red herring because the real indicator is whether the folder is nested inside the actual OneDrive-Personal structure in the File Explorer navigation; not just whether the word OneDrive appears somewhere in a path string. Saying OneDrive hijacks your desktop is probably too strong misleading or emotionally charged wording since Microsoft designs it this way as an optional backup feature that many users want and can turn off if desired a more neutral accurate way to phrase would be something like in most cases creating a PST-safe folder directly on your standard visible desktop does not guarantee a truly local non-synced setup because that desktop is often the cloud-backed one so to be safe for Outlook classic PST files it is better to create or use dedicated local folders outside the OneDrive tree.
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Jay Korobow 25 Reputation points

2026-01-24T09:14:37.23+00:00

not so simple: I originally thought creating a new folder directly on my visible desktop (the one I get when I show desktop or Win+D) would yield a plain boring normal local safe spot with no global cloud ties suitable for PST files to avoid any KB5 OneDrive Outlook mayhem – turned out FALSE for me. I have since learned that in most modern Windows 11 setups like mine with OneDrive known folder move enabled for Desktop that visible desktop surface is actually the redirected cloud-synced version living under OneDrive-Personal. Thus any folder I create there even if I name it something innocent like LOCALFOLDER or PST_SAFE ends up being cloud-bound with files subject to sync upload potential conflicts Files On-Demand interference and the usual PST corruption risks being popularly discussed. My initial assumption that plain old desktop equals automatically safe local was incorrect and the existence of OneDrive in some longer paths I saw for my Outlook data files was indeed a red herring because the real indicator is whether the folder is nested inside the actual OneDrive-Personal structure in the File Explorer navigation; not just whether the word OneDrive appears somewhere in a path string. Saying OneDrive hijacks your desktop is probably too strong misleading or emotionally charged wording since Microsoft designs it this way as an optional backup feature that many users want and can turn off if desired a more neutral accurate way to phrase would be something like in most cases creating a PST-safe folder directly on your standard visible desktop does not guarantee a truly local non-synced setup because that desktop is often the cloud-backed one so to be safe for Outlook classic PST files it is better to create or use dedicated local folders outside the OneDrive tree.
GFL4 75 Reputation points

2026-01-24T15:06:14.0033333+00:00

Would uninstalling one drive work?
Peter Marshall 5 Reputation points

2026-01-24T15:13:23.8533333+00:00

I ended up calling MS support and they remoted in to my desktop and after 90 minutes they had my email up and running again. They did many things, including manually removing the windows update, moving my PST out of One Drive and also setup a new account and moved everything over. Quite the ride.

I have my windows updates paused for now, but not sure when I need to release it and perhaps suffer the same fate again?

I will say that MS support was very patient with me and kind.
Hornblower409 7,005 Reputation points

2026-01-24T15:37:39.24+00:00

@GFL4 said

Would uninstalling one drive work?

[Answer edited by author 2026-01-24 16:41 UTC]

I don't know. This is not one of the approved workarounds. Proceed at your own risk.
Hornblower409 7,005 Reputation points

2026-01-24T15:41:28.29+00:00

@Peter Marshall said

I have my windows updates paused for now, but not sure when I need to release it

Monitor the official Microsoft Support page for this bug at
https://support.microsoft.com/en-us/office/classic-outlook-pop-account-profiles-hang-and-freeze-after-windows-11-update-to-kb5074109-590fe356-ecc2-49f4-b9e3-bd39fafa58f6

This will tell you when the problem has finally been solved and when it is safe to resume Windows Updates.
G Arthur 15 Reputation points

2026-01-24T16:57:21.9933333+00:00

Thank you Hornblower409 - no I didn't try the other fixes initially as i had assumed that the MS tech support agent had done everything necessary in my case... I have tried to follow your advice but after moving PSTs as suggested and making the new file the Default it won't let me Remove the OneDrive version it says 'You cannot delete this Outlook data file. Configuration information in the file is being copied to your new default file. You can delete the file after this information is copied' - that was a long time ago and it sill gives this message so presumably it is not able to copy or finish copying the config data? Consequently it is showing all the folders etc twice and has not solved the problem as the OneDrive file is still connected - can you please advise how to get out of this safely?

I have repeated the process a few times to try to get it to work and during these attempts somehow the archive PST file seems to have reverted to a really old version which also seems to have overwritten the OneDrive copy as well, even though the OneDrive version history is saying that it was last updated on Tuesday not today!!! Any thoughts on how I might be able to retrieve the situation? (I have thought about restoring a previous OneDrive version but was reluctant to do that without taking advice first as the date of the latest version doesn't make any sense..)

Also tried to download the OneDrive version of the archive PST file (5.5GB) to the location outside OneDrive to see what it actually contains but it doesn't complete the download and you get a 0 bytes PST file plus an incomplete xxxxxx.pst.part file a fraction of the size of the original file?

Help please!
Hornblower409 7,005 Reputation points

2026-01-24T17:22:22.4933333+00:00

@G Arthur said

it won't let me Remove the OneDrive version

I am sorry. But this kind of problem is not one that lends itself to debugging via forum post.

I would suggest you contact Microsoft Support so they can remote into your PC and examine your current environment.

MS 365 User Support https://www.microsoft.com/en-us/microsoft-365/support

Free Chat Support https://support.microsoft.com/home/contact
Jay Korobow 25 Reputation points

2026-01-25T01:24:35.7933333+00:00

MS announced KB5078127 today as the BIG FIX we all were awaiting for Outlook Classic PST mayhem related to that forced update a week or so ago. It promised it would show up for those that had the earlier mishap upd, and sure enough it did and i installed it and rebooted. A minimal amount of testing but so far looks real good. TY all.
Mirka Breen 55 Reputation points

2026-01-25T02:02:35.9566667+00:00

Please, users who were affected (like me) and uninstalled the Jan 13 update (like me, finally on Jan 15) and have now resumed updates and got the latest KB5078127 "fix" and have everything running as it should, PLEASE POST HERE. I am too chicken to try this and risk an unfunctional email again or something else go awry while the easy way recommended by Microsoft to uninstall updates just isn't there. It was too much for many of us. Do tell us how it's going.
Hornblower409 7,005 Reputation points

2026-01-25T02:14:23.79+00:00

References for the Out Of Band Update KB5078127

https://support.microsoft.com/en-us/topic/january-24-2026-kb5078127-os-builds-26200-7628-and-26100-7628-out-of-band-cf5777f6-bb4e-4adb-b9cd-2b64df577491

https://learn.microsoft.com/en-us/windows/release-health/status-windows-11-25h2#2738msgdesc
GFL4 75 Reputation points

2026-01-25T02:37:14.97+00:00

Just installed update without any problems. Sent test email with attachment. Outlook closes normally and disappears from task mgr. all good.
TTraynor 0 Reputation points

2026-01-25T18:02:36.7466667+00:00

I uninstalled KB5074109 and everything is working again
Jim Smith 5 Reputation points

2026-01-25T20:09:13.37+00:00

Same for me - 5 days wasted trying to find out issue and it turns out to be Microsofst own update!

Managed to uninstall the update and pause MS updates until they confoirm they have fixed this
Hornblower409 7,005 Reputation points

2026-01-25T21:17:16.6366667+00:00

@TTraynor said

I uninstalled KB5074109 and everything is working again

There is a new update KB5078127 that is a fix for the KB5074109 bug. See my Answer "Hornblower409 Jan 24, 2026, 9:29 PM" further down in this thread.
Hornblower409 7,005 Reputation points

2026-01-25T21:34:27.9566667+00:00

@Jim Smith said

uninstall the update and pause MS updates until they confoirm they have fixed this

A fix for the KB5074109 Outlook/OneDrive bug has been released as KB5078127.

https://support.microsoft.com/en-us/topic/january-24-2026-kb5078127-os-builds-26200-7628-and-26100-7628-out-of-band-cf5777f6-bb4e-4adb-b9cd-2b64df577491
Paula Snyder 0 Reputation points

2026-01-26T14:40:42.62+00:00

I have uninstalled the faulty Security update SEVERAL TIMES. I have avoided letting WINDOWS install it for now - but WINDOWS keeps FORCING the installation! I had updates on hold and was shutting down without the updates. I kept delaying the installation of that particular update, but it overrode me and did it anyway.

I have tried the "NEW" Outlook - but all my files and history are in Classic. I can't arrange the e-mail accounts the way I want to on that platform, and it won't accept / show the signatures I created for each e-mail address in the new platform. I don't have time to redo everything - and I am hoping that Microsoft comes back with a fix for how that Security update from 1/14/26 works with Classic Outlook.
Gabe Bratton 686 Reputation points Microsoft Employee Moderator

2026-01-26T14:49:30.6566667+00:00

@Hornblower409 , I just updated the article. I apologize for the delay. I tested the fix late Friday for fix verification. It worked fine in my tests. Please let me know if you see any issues. Thank you for sharing guidance and helping others in this thread.

https://support.microsoft.com/en-us/office/classic-outlook-profiles-with-pop-accounts-and-psts-hang-after-windows-updates-on-january-13-2026-590fe356-ecc2-49f4-b9e3-bd39fafa58f6
Hornblower409 7,005 Reputation points

2026-01-26T14:55:21.4833333+00:00

@Paula Snyder said

I am hoping that Microsoft comes back with a fix for how that Security update from 1/14/26 works with Classic Outlook

There is a fix for the problems caused by the 1/14/26 update KB5074109. It has been released as KB5078127.

https://support.microsoft.com/en-us/topic/january-24-2026-kb5078127-os-builds-26200-7628-and-26100-7628-out-of-band-cf5777f6-bb4e-4adb-b9cd-2b64df577491

You should be able to resume your Windows Updates, do a Check for Updates, and KB5078127 should be offered in the list of updates available for "Download & Install".
ALICIA ELENA CURIEL CORDERO 10 Reputation points

2026-01-26T16:25:11.8+00:00

i installed the last update, no changes at all :(
Gabe Bratton 686 Reputation points Microsoft Employee Moderator

2026-01-26T16:33:18.7033333+00:00

@ALICIA ELENA CURIEL CORDERO double check Windows Update History shows you got KB5078127. If you have it and still repro try restarting Windows. This update should fix the issue if it's the bug in KB5074109.
Gabe Bratton 686 Reputation points Microsoft Employee Moderator

2026-01-26T17:38:56.0233333+00:00

@ALICIA ELENA CURIEL CORDERO If you are having any issues with sync or related after installing the update try repairing the Outlook profile:

Click File, Account Settings, Account Settings, click on the POP account, click Repair. I saw some issues like this in my testing.
ALICIA ELENA CURIEL CORDERO 10 Reputation points

2026-01-26T18:35:02.6066667+00:00

@Gabe Bratton finally!! my Outlook is back!! Thanks so much Gabe and Hornblower!!
Jim Smith 5 Reputation points

2026-01-28T15:09:30.1733333+00:00

So after successfully installing patch KB5078127 and Outlook workimg fine for a few days, today the same issues have started again with Outlook freezing when I click on a different account, or sometimes even when just sitting there.

Do I still need to move .pst files out of OneDrive?
Junior Mangoo 0 Reputation points

2026-01-29T10:32:53.47+00:00

i also face the same problem, after updating it is hang constantly and also facing issues while installing.
Hornblower409 7,005 Reputation points

2026-01-29T12:03:21.59+00:00

@Junior Mangoo said

i also face the same problem, after updating it is hang constantly and also facing issues while installing.

This thread is for problems you get before you installed the latest Windows Update. If you have either KB5078127 or KB5078129 then please use the "Ask a question" button at the top of this page and start a new thread for your specific problems. It will get much better visibility than commenting in this older thread.
ScottA 20 Reputation points

2026-01-30T02:02:43.9366667+00:00

I’m despairing here. I can’t access the new updates. Support won’t call or respond; just mark every request as resolved. I try asking new questions and the content is deleted (as I assume this will be). Microsoft has broken my email and I can’t find anyway back to fix it . . HELP!!!!!
Hornblower409 7,005 Reputation points

2026-01-30T03:48:00.8733333+00:00

@ScottA said

I can’t access the new updates.

1 -- Try the Windows Update Troubleshooter
https://support.microsoft.com/en-us/windows/windows-update-troubleshooter-19bc41ca-ad72-ae67-af3c-89ce169755dd

2 -- Last Resort - Use the Microsoft/Windows Update Catalog

! Create a System Restore Checkpoint !

https://support.microsoft.com/en-us/windows/system-protection-e9126e6e-fa64-4f5f-874d-9db90e57645a

Read this first:

https://learn.microsoft.com/en-us/troubleshoot/windows-client/installing-updates-features-roles/download-updates-drivers-hotfixes-windows-update-catalog

Search the catalog

https://www.catalog.update.microsoft.com/Home.aspx

KB5078127 for Windows 11, KB5078129 for Windows 10. Be sure to pick the one for your Windows Version and your CPU architecture.

I try asking new questions and the content is deleted (as I assume this will be)

Microsoft only delete Q&A post for a violation of the Terms & Conditions. Normally you have to be pretty egregious to get deleted. But there have been some problems with the filter software lately that may have taken down your post in error. Best chances for not getting smacked is to keep your post short and in plain text (no links or images).
Hornblower409 7,005 Reputation points

2026-01-30T03:52:17.55+00:00

@ScottA said

Support won’t call or respond

If you can't get any help from phone support, try on-line Chat support.

MS 365 Subscriber https://www.microsoft.com/en-us/microsoft-365/support
All others https://support.microsoft.com/home/contact
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Answer accepted by question author

Suncoast Information Systems 310 Reputation points

2026-01-15T14:58:38.0166667+00:00

Uninstalling KB5074109 worked for us on several PCs
Please sign in to rate this answer.

40+ people found this answer helpful.
Dan Brown 35 Reputation points

2026-01-15T21:34:12.2233333+00:00

I was able to uninstall this update in the Windows control panel. No tricky steps as Hornblower409 mentioned. How can Microsoft break one of their own products with a security update. I understand a 3rd party product, but millions of people use Outlook Classic and POP3.

David Mullins 0 Reputation points

2026-01-15T21:59:47.52+00:00

i'm not an advanced user

AlistairJT 25 Reputation points

2026-01-15T22:09:05.5333333+00:00

David - try the easy way - Go to "Windows Update" from your search and then Update History - you will hopefully see when you scroll down an Uninstall Updates option. Within there look for KB5074109 and uninstall it. That worked for me.

Hornblower409 7,005 Reputation points

2026-01-16T04:45:22.6+00:00

@David Mullins said

i'm not an advanced user [can't use the dism command line answer I provided]

There are other suggestions in this thread.

@AlistairJT and @John W

Windows Update -> Update History -> Uninstall Updates. It was listed there for me and I was able to uninstall it without issue.

@Mirka Breen

Control Panel, then to Programs, then on the left side find updates

@Chris Seagrave

do a System Restore .. the restore point had been automatically been set on 13th January before the 2026-01 Security Update (KB5074109)

Jamie 0 Reputation points

2026-01-16T10:47:50.7666667+00:00

Same here

Mary Hodges 15 Reputation points

2026-01-16T11:18:30.2766667+00:00

I spent the whole of yesterday and 3 hours this morning with various updates, etc and nothing worked. Uninstalled update and bingo back to normal. The update was hidden at the bottom in security updates with big warnings not to uninstall but at this point the laptop was about to go into the bin so I had nothing to lose.

GFL4 75 Reputation points

2026-01-16T14:04:01.3966667+00:00

Tried to find this update. No uninstall feature in windows history although i see update. Not listed through control panel. While microsoft fixes why dont they give us a rollback update or something we click on that rolls update back?

Bryan Delp 30 Reputation points

2026-01-16T14:22:57.46+00:00

See Hornblower409 instructions below. It worked for me. Thanks!

Jay Emerson 5 Reputation points

2026-01-16T16:07:46.9933333+00:00

@AlistairJT triggered me to KEEP scrolling down in Settings. Thank you.

michael kleiman 0 Reputation points

2026-01-16T16:08:05.87+00:00

I have the same problem, and see that KB5074109 was installed this week, but I don't see it listed as one of the updates available to uninstall (earlier Windows updates from December are available to uninstall). I am not an "advanced user", so don't feel competent to go in as administator and make edits. What other advice do you have for uninstalling or some other resolution?

PS - I spent hours on this, and created a new OST file which seems to have helped, but not completely resolved the problem.

GFL4 75 Reputation points

2026-01-16T16:27:09.0433333+00:00

There is nothing to do but wait for Microsoft to fix issue. Hopefully soon. Uninstall not avail in update history and not listed under program etc. and i am not an advanced user either.

Chris Hadley 10 Reputation points

2026-01-16T16:50:15.6666667+00:00

Don't we just love Microsoft. I had the same issue. Outlook was buggy all of the 15th and on closing wouldn't re-open unless I did a PC restart. It developed today (Friday) into not showing sent emails since the 15th, refusing to delete everything that had been deleted from 11.30GMT on the 15th and ultimately not sending any emails, including a proposal. My wife (more non-tech than me) suggested updates and on searching the system on the PC I uninstalled KB6074109. PC automatically re-started, did some sort of restore and bingo it works!!! Not sure of the implications of this uninstall but I have a business to run - I'll be calling my engineer Monday am. Best of luck everyone.

GFL4 75 Reputation points

2026-01-16T17:15:43.28+00:00

Microsoft, please roll this back for us users who are not advanced and cant uninstall from history or programs.

Tony 10 Reputation points

2026-01-16T20:12:31.8+00:00

Fixed mine as well after s lot of wasted hours trying other fixes

Harry Chapman 5 Reputation points

2026-01-16T20:57:07.51+00:00

I uninstalled the latest update and now I am fine. Please test your updates before you issue them. This is unacceptable!

SAEED ANWAR 0 Reputation points

2026-01-16T21:04:08.2833333+00:00

Uninstalling KB5074109 resolved the issue. No more hangs or freeze

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MandyW 5 Reputation points

2026-01-17T06:59:43.02+00:00

Also just managed to uninstall the latest Security Update by Windows on 14 January 2026. Of course after various other initial options. VERY FRUSTRATING MICROSOFT! Please sort out this BUG!
We are aware it's a security risk, but have no other option in order to keep Outlook running at this stage. We eagerly await a corrected Security Update, Microsoft.

Hornblower409 7,005 Reputation points

2026-01-17T12:15:57.87+00:00

@Jamie said

Same here

In a long thread like this one it can be hard to be sure what you are commenting on. Could you provide any other details on exactly what is the same for you? Other than that you are seeing the same issue as everyone else.

Hornblower409 7,005 Reputation points

2026-01-17T12:29:20.84+00:00

@MandyW said

Please sort out this BUG!

To assist @Gabe Bratton from Microsoft, who is working on this issue, could you tell us:

Are you using OneDrive and if so, is your Outlook POP PST file in a OneDrive folder?

To find the location of your Outlook POP PST: Right-Click on the top level folder for your POP account and choose "Data File Properties", [Advanced]. Is the "Filename" in a OneDrive folder?

GFL4 75 Reputation points

2026-01-17T14:49:54.9866667+00:00

Would it help to just pause one drive and then test? Too many pst files in onedrive to remive.

Hornblower409 7,005 Reputation points

2026-01-17T15:00:54.2133333+00:00

@GFL4 said

Would it help to just pause one drive and then test?

Sure. This is a bug hunt. Try anything that won't trash your system and let us know the outcome. Every bit of data helps. Even if it's "Well that didn't work".

Chris Maher 0 Reputation points

2026-01-17T23:58:13.7433333+00:00

But Windows keeps reinstalling it! How do you stop that?

Neil Bester 5 Reputation points

2026-01-18T13:23:01.3733333+00:00

Confirmed this fix works for now (until MS fixes it properly). For those struggling - the uninstall option is NOT under Update History. Rather, search for "Uninstall Updates" and you can uninstall it from that menu.

GFL4 75 Reputation points

2026-01-18T16:27:42.7866667+00:00

Not there either. In fact my windows 11 doesnt show any updates post post 4/11/2025. Where could they be hidden?

Hornblower409 7,005 Reputation points

2026-01-18T18:01:44.6233333+00:00

@GFL4 said

Not there either. In fact my windows 11 doesnt show any updates post 4/11/2025. Where could they be hidden?

I assume you a looking for KB5074109?

If so, from a Command Prompt execute wmic qfe list brief
If you don't see it there, you don't have it?

GFL4 75 Reputation points

2026-01-18T18:19:36.66+00:00

Found it there. Will wait a few days to try to uninstall using wusa

SanDiego7777 5 Reputation points

2026-01-18T22:04:48.0266667+00:00

Worked for me. However, Windows wanted to reinstall the KB almost right away - paused updates for a week, hoping MS fixes soon

Chris Maher 0 Reputation points

2026-01-18T22:07:41.3266667+00:00

that's exactly what happened to me @sandeigo7777. I've paused for a week and hope that MS fixes this bug and sends out a new patch before then.

Ward12 0 Reputation points

2026-01-18T22:07:51.85+00:00

I had the same issue and have spent well over 10 hours trying to solve it. After uninstalling KB5074109 the outlook is fixed, but now it breaks the Microsoft XPS Document Writer v4 Printer in windows 11. I have tried all the recommended fixes and it just gives error Ox800F0922 when selecting the box under optional features which means I need the security update. Tried also to add it under printers and settings and it doesn't find XPS printer writer even using Microsoft update. Even running a MS365 offline repair it doesn't fix the XPS writer

Hornblower409 7,005 Reputation points

2026-01-19T00:20:21.0766667+00:00

@Ward12 said

uninstalling KB5074109 breaks the Microsoft XPS Document Writer

I would suggest that you either start a new thread for this issue using the "Ask a question" button at the top of this page. or contact Microsoft Support https://support.microsoft.com/home/contact

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Marlena 0 Reputation points

2026-01-20T13:51:47.2433333+00:00

I had to unistall the KB5074109 update as well after experiencing issues with my Outlook. Terrible experience on Microsoft laptop with Microsoft Windsows 11 OS and Microsoft Outlook software. Do they not test before releasing the updates?!

Richard Heiles 0 Reputation points

2026-01-20T17:49:05.6866667+00:00

Uninstalling KB5074109 worked for me also. I cannot believe that Microsoft techs cannot figure this out themselves and send out a new update. Two days of wasting time trying to figure this out. Wonder why I pay them a licensing fee.

DIM 0 Reputation points

2026-01-20T22:20:58.9433333+00:00

I had the same problem and this solved my issue. "Uninstalling the update KB5074109 fixed it for me! I am now able to close outlook gracefully, reopen it, and all of my progress is saved."

Jane Holcombe 5 Reputation points

2026-01-20T23:29:26.4066667+00:00

Uninstall failed. Several times.

Fern-C 0 Reputation points

2026-01-20T23:32:38.4533333+00:00

Great thread, I honestly tried everything to remove the Security Update KB5074109 with no luck. It was freezing my Outlook 365. However, I was able to unlink OneDrive from Microsoft 365, and my Outlook is working normally without having to delete the security update, and I kept the POP3 email setting. It worked for both my computers. Hope this helps anyone who may be having the same issue. Hopefully, Microsoft will come up with a repair soon so we can use OneDrive again.

Hornblower409 7,005 Reputation points

2026-01-21T01:36:48.2766667+00:00

@Jane Holcombe said

Uninstall failed. Several times.

All I can suggest is to contact Microsoft Support. Your questions should be something like "Can not uninstall KB5074109"

MS 365 - User Support
https://www.microsoft.com/en-us/microsoft-365/support

Free Chat Support
https://support.microsoft.com/home/contact

And reference this Support article so they know what you are trying to fix. https://support.microsoft.com/en-us/office/classic-outlook-pop-account-profiles-hang-and-freeze-after-windows-11-update-to-kb5074109-590fe356-ecc2-49f4-b9e3-bd39fafa58f6

Or try the alternative fix of moving your PST files out of your OneDrive directory.
https://support.microsoft.com/en-us/office/how-to-remove-an-outlook-pst-data-file-from-onedrive-b6b9e522-59bd-40f7-949f-168d0aa9b38e

You may also need to use ScanPST to correct any errors in the PST files.
https://www.slipstick.com/problems/pst-repair/repair-a-damaged-personal-folders-pst-file/

Jim Cofer 25 Reputation points

2026-01-21T01:41:15.1633333+00:00

@Jane Holcombe Is Windows Sandbox installed on the PC? If so, uninstall Sandbox then try again.

ALICIA ELENA CURIEL CORDERO 10 Reputation points

2026-01-21T19:30:11.6433333+00:00

i did unistalled it but Outlook kept crashing, i downloaded Thunderbird in the meantime but now i can´t access to my PST files trough Thunderbird. I just wish they develop a Patch so we can return to Outlook cuz all of my data is in those PST.

Hornblower409 7,005 Reputation points

2026-01-21T20:02:35.4133333+00:00

@ALICIA ELENA CURIEL CORDERO said

i did unistalled it but Outlook kept crashing

There are a lot of reasons why Outlook will crash that have nothing to do with KB5074109. I don't want to go into all the possibilities here but two quick ones are:

Start Outlook in Safe Mode
https://support.microsoft.com/en-us/office/open-outlook-in-safe-mode-f394c2ee-b2af-e97a-64ee-35cd24414811

Outlook Repair
https://support.microsoft.com/en-us/office/repair-an-office-application-7821d4b6-7c1d-4205-aa0e-a6b40c5bb88b

The other thing to try is to Move any PST files out of your OneDrive folder and use ScanPST to check for errors.

To see the locations of your PST files:

From the Outlook menu do File > Account Settings > Account Settings. Select the "Data Files" tab.

If your Outlook is not useable - Open the Windows Control Panel. Click on the "Mail" link. On the "Mail Setup" dialog click "Data Files ..."

How to remove an Outlook .pst data file from OneDrive

https://support.microsoft.com/en-us/office/how-to-remove-an-outlook-pst-data-file-from-onedrive-b6b9e522-59bd-40f7-949f-168d0aa9b38e

ScanPST

https://learn.microsoft.com/en-us/troubleshoot/outlook/data-files/how-to-repair-personal-folder-file

Once you have moved all of your PSTs you can resume Windows Updates. KB5074109 won't break your Outlook.

i downloaded Thunderbird in the meantime but now i can´t access to my PST files

The only way to use PSTs with a non-Microsoft client (that I know of) involve third party tools that let you import the data from your PSTs into the client's native storage.

If you want to try that route, a web search for email clients other than Outlook that can use PST files should get you some links.

Mirka Breen 55 Reputation points

2026-01-21T20:34:32.1233333+00:00

@Hornblower409, for those on this forum who are technical, trying the many things discussed in order to convey information to @Gabe Bratton is fine. But as you said initially, if we are not experts we shouldn't do any of these things, and most users are not. We are awaiting the promised update from MS's Gabe promised to be posted yesterday Jan 20 as to what progress if any they have made. Uninstalling and freezing updates for now is the ONLY relevant action for most of us, and it is not a solution for long. Thank you for trying and hanging out here, but PLEASE make sure to update what's next for most users.

Hornblower409 7,005 Reputation points

2026-01-21T23:28:37.43+00:00

@Mirka Breen said

Uninstalling and freezing updates for now is the ONLY relevant action for most of us ... make sure to update what's next for most users

@Gabe Bratton updated the Support Article to include another fix (below). But there is still no final resolution.

https://support.microsoft.com/en-us/office/classic-outlook-pop-account-profiles-hang-and-freeze-after-windows-11-update-to-kb5074109-590fe356-ecc2-49f4-b9e3-bd39fafa58f6

If you are uncomfortable performing the steps to move your PST files, all I can suggest is that you contact Microsoft Support and ask them to help. Reference the Support.Microsoft article above and the steps in this comment.

MS 365 - User Support
https://www.microsoft.com/en-us/microsoft-365/support

Free Chat Support
https://support.microsoft.com/home/contact

Move any PST files out of your OneDrive folder and use ScanPST to check for errors.

To see the locations of your PST files:

From the Outlook menu do File > Account Settings > Account Settings. Select the "Data Files" tab.

If your Outlook is not useable - Open the Windows Control Panel. Click on the "Mail" link. On the "Mail Setup" dialog click "Data Files ..."

How to remove an Outlook .pst data file from OneDrive

https://support.microsoft.com/en-us/office/how-to-remove-an-outlook-pst-data-file-from-onedrive-b6b9e522-59bd-40f7-949f-168d0aa9b38e

ScanPST

https://learn.microsoft.com/en-us/troubleshoot/outlook/data-files/how-to-repair-personal-folder-file

Once you have moved all of your PSTs you can resume Windows Updates. KB5074109 won't break your Outlook.

nyjklein 50 Reputation points

2026-01-22T21:34:20.2466667+00:00

I'm on Win 11 Insiders Beta track, version 26220.7535, I don't have KB5074109. But I do have KB5074157 installed on Jan 16. I assume this is the equivalent and uninstalling it should have the desired effect?

Update: Removing KB5074109 resolved the issue for me! And I've provided feedback and added a question in the insiders Q&A.

Hornblower409 7,005 Reputation points

2026-01-22T22:53:14.35+00:00

@nyjklein said

I don't have KB5074109. But I do have KB5074157 [Windows 11 Insider Preview Build 26220.7653 (Beta Channel)] uninstalling it should have the desired affect?

I would suggest you:

Post a question on the Windows Insider Q&A
https://learn.microsoft.com/en-us/answers/tags/953/windows-insider

Or use the Windows Feedback Hub

https://blogs.windows.com/windows-insider/2026/01/21/announcing-windows-11-insider-preview-build-26220-7653-dev-channel/

Please share your feedback in Feedback Hub (WIN + F) under “Settings -> User Profile Account Settings.

S Puma 0 Reputation points

2026-01-24T13:49:25.6666667+00:00

uninstalling the windows update KB5074109 did not work for me

Hornblower409 7,005 Reputation points

2026-01-24T15:16:36.9633333+00:00

@S Puma said

uninstalling the windows update KB5074109 did not work for me

Have you tried the other workaround?

Move any PST/OST files out of your OneDrive folder and use ScanPST to check for errors. How to remove an Outlook .pst data file from OneDrive
https://support.microsoft.com/en-us/office/how-to-remove-an-outlook-pst-data-file-from-onedrive-b6b9e522-59bd-40f7-949f-168d0aa9b38e ScanPST
https://learn.microsoft.com/en-us/troubleshoot/outlook/data-files/how-to-repair-personal-folder-file

If you have tried both workarounds and you are still having problems

Use the "Ask a question" button at the top of this page and start a new thread that describes your issue. Be sure to include in your problem description that you have already tried both workarounds for the KB5074109 Outlook problem.

Or contact Microsoft Support directly:

MS 365 User Support https://www.microsoft.com/en-us/microsoft-365/support
Free Chat Support https://support.microsoft.com/home/contact

Paula Snyder 0 Reputation points

2026-01-26T14:42:59.0133333+00:00

It doesn't stay UNINSTALLED!

Stefan Blom 337.4K Reputation points MVP Volunteer Moderator

2026-01-26T14:46:13.6666667+00:00

@Paula Snyder, install the recent update which reportedly fixes the underlying issue. See https://support.microsoft.com/en-us/topic/january-24-2026-kb5078127-os-builds-26200-7628-and-26100-7628-out-of-band-cf5777f6-bb4e-4adb-b9cd-2b64df577491 . The update should appear in Windows Update if you make a search.

Answer recommended by moderator

Hornblower409 7,005 Reputation points

2026-01-25T03:29:40.27+00:00

January 24, 2026 - KB5078127 (OS Builds 26200.7628 and 26100.7628) Out-of-band
Fix for Outlook/OneDrive Issues.

https://support.microsoft.com/en-us/topic/january-24-2026-kb5078127-os-builds-26200-7628-and-26100-7628-out-of-band-cf5777f6-bb4e-4adb-b9cd-2b64df577491

I have installed KB5078127 and (so far) I am not seeing any problems.

Just resume your Windows Updates, check for updates, and it should offer you KB5078127.

As I understand it, you do not need to re-install KB5074109 if you previously removed it.
Please sign in to rate this answer.

5 people found this answer helpful.
Hornblower409 7,005 Reputation points

2026-01-25T03:53:30.6833333+00:00

@Gabe Bratton
The Support page for this bug, that I have been telling everyone to monitor for the "All Clear", has not been updated yet.

https://support.microsoft.com/en-us/office/classic-outlook-profiles-with-pop-accounts-and-psts-hang-after-windows-updates-on-january-13-2026-590fe356-ecc2-49f4-b9e3-bd39fafa58f6

If it's appropriate to update the page at this time, is this something that you can help with?

Mirka Breen 55 Reputation points

2026-01-25T19:05:56.1933333+00:00

@Hornblower409 and @Gabe Bratton I resumed updates and to my chagrin the first thing the old defective KB5074109 re-installed (after I had uninstalled in Jan 15) and it took almost half an hour later for the fix KB5078127 to show up as ready/available to install. Right now (thirty minutes post fix installation) Outlook Classic is working. But the future is unclear to me as this particular thread has gone silent with no more are chiming in if there are issues a day post fix. {it took almost a day for the issues to arise after the KB5074109, and I did use my Outlook on 1/13 AND 1/14 a few times before it began to act up.) Thank you both for working on this, and I'll be here again IF new issues arise. Let us hope not.

Hornblower409 7,005 Reputation points

2026-01-25T21:32:37.31+00:00

@Mirka Breen said

But the future is unclear to me as this particular thread has gone silent with no more are chiming in

Day two of KB5078127 and everything is good for me.

Fred 5 Reputation points

2026-01-26T06:54:45.92+00:00

I just tried to resume updates, but KB5078127 was not offered to me. Maybe an issue for non-English language versions?

Cheers and thanks again for the hot fix information @Hornblower409 !

Hornblower409 7,005 Reputation points

2026-01-26T12:02:59.4133333+00:00

@Fred said

I just tried to resume updates, but KB5078127 was not offered to me

For me, after Resume Updates, I also had to do "Check Updates" and then KB5078127 showed up as available. I had to select it and Download & Install.

Maybe an issue for non-English language versions?

As far as I know, this was released "globally". I would suggest you wait another day for it to become available for you.

If you still don't get it, I would suggest you contact Microsoft Support.

MS 365 User Support https://www.microsoft.com/en-us/microsoft-365/support
Free Chat Support https://support.microsoft.com/home/contact

Fred 5 Reputation points

2026-01-26T12:41:27.7766667+00:00

@Hornblower409 , will do. Thanks for your incredibly helpfull assitance!

Gabe Bratton 686 Reputation points Microsoft Employee Moderator

2026-01-26T14:53:00.4466667+00:00

@Hornblower409 , I just updated the article. I apologize for the delay. I tested the fix late Friday for fix verification. It worked fine in my tests. Please let me know if you see any issues. Thank you for sharing guidance and helping others in this thread.

https://support.microsoft.com/en-us/office/classic-outlook-profiles-with-pop-accounts-and-psts-hang-after-windows-updates-on-january-13-2026-590fe356-ecc2-49f4-b9e3-bd39fafa58f6

Pamela Kerr 20 Reputation points

2026-01-26T19:55:12.9833333+00:00

I uninstalled the KB5074109 which fixed my problem. Then it came back - I uninstalled for a 2nd and 3rd time, so I paused for a week. Then I saw the fix so I went to my updates and there was the culprit again! I tried to delete and got an error message so I've paused....again....and was wondering if I should let it run through, install it and then run the fix update, if it shows up. I'd hate to lose the functionality that I worked so hard to get. I also don't want to have to go back and recreate the wheel, if you will, by doing a reset point!

Gabe Bratton 686 Reputation points Microsoft Employee Moderator

2026-01-26T20:12:30.97+00:00

@Pamela Kerr let the Windows Updates install the latest updates. The fixed update will automatically install as KB5078127. The update fixes the issues caused by KB5074109. The feedback has been positive. Let me know if you find otherwise.

Here is the Outlook Known Issue for reference, https://support.microsoft.com/en-us/office/classic-outlook-profiles-with-pop-accounts-and-psts-hang-after-windows-updates-on-january-13-2026-590fe356-ecc2-49f4-b9e3-bd39fafa58f6.

Hornblower409 7,005 Reputation points

2026-01-26T20:15:58.6233333+00:00

@Pamela Kerr said

Then I saw the fix so I went to my updates and there was [KB5074109] again

Close Outlook and keep it closed while you are playing the Windows Update Game.

Create a System Restore Point
(Windows Update should do this for you, but I like to have my own)
https://support.microsoft.com/en-us/windows/system-protection-e9126e6e-fa64-4f5f-874d-9db90e57645a

Resume Windows Updates.

If it wants to re-install KB5074109, let it.

You should see KB5078127 or KB5078129, either auto installed or offered to you for "Download & Install". Once you have either you are in the clear.

If you do not get KB5078127 or KB5078129:

Do a System Restore
(This puts you back the way you were)
https://support.microsoft.com/en-us/windows/system-restore-a5ae3ed9-07c4-fd56-45ee-096777ecd14e

And then contact Microsoft Support. Ask "I can not get KB5078127 or KB5078129".

MS 365 User Support https://www.microsoft.com/en-us/microsoft-365/support

Free Chat Support https://support.microsoft.com/home/contact

ScottA 20 Reputation points

2026-01-27T07:41:41.42+00:00

Is the fix KB5078127 released just for Windows 11? (Sorry if this is a dumb question . . I'm a total novice), If so, is there something coming for Windows 10?

I had this problem appear 2 weeks ago but was fixed with the removal of the offending update by Microsoft support. The whole problem came back again between me logging off on the 22nd Jan and logging back in on the 26th. 2 attempts with Microsoft support today got nowhere - they are just advising to wait for a fix but Gabe's article says it is fixed. Help . . ?

Fred 5 Reputation points

2026-01-27T07:50:34.4066667+00:00

Hello @Hornblower409 and everyone else,

I had to install the buggy KB5074109, reboot and then patiently wait for sth. like 5 mins before the bug fix KB5078127 was offered to me ( I manually checked for available updates twice until it was available for download) . It is installing while I am writing this.

This community is great. Thank you!

Hornblower409 7,005 Reputation points

2026-01-27T09:45:33.5866667+00:00

@ScottA said

Is the fix KB5078127 released just for Windows 11? is there something coming for Windows 10?

KB5078129 is the equivalent for Windows 10.

Close Outlook and keep it closed while you are playing the Windows Update Game.

Create a System Restore Point (Windows Update should do this for you, but I like to have my own)

https://support.microsoft.com/en-us/windows/system-protection-e9126e6e-fa64-4f5f-874d-9db90e57645a

Resume Windows Updates.

If it wants to re-install KB5074109, let it.

You should see KB5078127 or KB5078129 either auto applied or offered to you for "Download & Install". Once you have either you are in the clear.

If you do not get KB5078127 or KB5078129:

Do a System Restore (This puts you back the way you were) https://support.microsoft.com/en-us/windows/system-restore-a5ae3ed9-07c4-fd56-45ee-096777ecd14e

And then contact Microsoft Support. Ask "I can not get KB5078127 or KB5078129".

MS 365 User Support https://www.microsoft.com/en-us/microsoft-365/support

Free Chat Support https://support.microsoft.com/home/contact

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H 0 Reputation points

2026-01-28T09:39:43.51+00:00

I have installed the update KB5078127 which is designed to fix this issue but I'm still getting all the issues I previously did/have been reported.

Outlook won't automatically repair settings and when I try to manually they just change back (not sure if email settings need changing as emails have been delivered ok but they do look different to those the email provider states).

What is the best way to get help???

Hornblower409 7,005 Reputation points

2026-01-28T09:49:23.03+00:00

@H said

I have installed the update KB5078127 ... but I'm still getting all the issues I previously did. What is the best way to get help?

Contact Microsoft Support:

MS 365 User Support https://www.microsoft.com/en-us/microsoft-365/support

Free Chat Support https://support.microsoft.com/home/contact

H 0 Reputation points

2026-01-28T11:41:34.4333333+00:00

I've just spent a very nervous 3 hours on web chat with Microsoft (it's uncomfortable letting someone take over your computer) - they say they deleted the offending update, removed Office software and re-updated it but after all that my Outlook situation is no different!!

Hornblower409 7,005 Reputation points

2026-01-28T11:59:02.7466667+00:00

@H said

but after all that [MS Support changes] my Outlook situation is no different!!

Obviously you have problems that go a lot deeper than most others on this thread, where KB5074109 was the source of all evil.

If MS Support couldn't fix it, all I can suggest is that you use the "Ask a question" button at the top of this page and start a new thread for your specific problems.

Be sure to give your current Outlook and Windows versions.

What version of Outlook do I have?
https://support.microsoft.com/en-us/office/what-version-of-outlook-do-i-have-b3a9568c-edb5-42b9-9825-d48d82b2257c Which version of Windows do I have?
https://support.microsoft.com/en-us/windows/find-information-about-your-windows-device-a66d52c8-3323-44fd-8f34-a9497bb935e1

When did the problems first start?

A concise description of the worst issues. You will be better served by focusing on the big stuff at this point and not get into all the minutiae.

H 0 Reputation points

2026-01-28T12:27:56.6066667+00:00

The problems all started straight after the offending update... and are the same as described here ie any actions that I take (eg moving emails into folders) aren't saved so they're all there again when I reopen Outlook; and it 'freezes/crashes' not long after opening - whilst using normally or even just sat there doing nothing for a short while.

Like some others, I can't uninstall the update as it's not available in the History. However, the MS service agent said he had done it another way (through both Control Panel - I'm not techie but as it was never available to uninstall I feel sceptical about this) - and also the "command‑line method".

I'm using Outlook Classic (with a pop email service) and am on Windows 11.

Pamela Kerr 20 Reputation points

2026-01-28T14:47:49.25+00:00

Thanks to all for the help! As a 72-year-old novice to computer tech... I've learned a lot about the inner workings of my laptop :) I learned how to do a recovery set point - how to uninstall an update - and how to move .pst folders off the OneDrive! By doing all of the above and installing the patch (which came up very shortly after I downloaded the evil update...lol), my POP3 email is working great...so far...Thanks again!! Will keep you posted on how things progress.

Jim Smith 5 Reputation points

2026-01-28T15:10:24.35+00:00

Problems have back again for me today (worked OK for 3 days after installing patch)

Hornblower409 7,005 Reputation points

2026-01-28T17:34:42.4833333+00:00

@H said

The problems all started straight after the offending update
I can't uninstall the update as it's not available in the History

I understand. But I still think you would be better served by using the "Ask a question" button at the top of this page and starting a whole new thread on your issues instead of commenting on this thread.

This thread is about removing the update or other common workarounds for the bad update in general, and your case needs special attention.

Hornblower409 7,005 Reputation points

2026-01-28T17:52:08.0233333+00:00

@Jim Smith said

Problems have back again for me today (worked OK for 3 days after installing patch)

This thread has grown to the point where it is really not effective for individual support. I would suggest that you use the "Ask a question" button at the top of this page and start a new thread on your issue of the problem reoccurring after patching.

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13 additional answers

Hornblower409 7,005 Reputation points

2026-01-15T05:07:23.3066667+00:00

How to uninstall KB5074109

These instructions are for Advanced Users Only. If you do not fully understand what is being done here, do not proceed.

KB5074109 is a combined package containing a Servicing Stack Update (SSU), so it cannot be uninstalled using the standard "Uninstall updates".

1 -- Open a Command Prompt as administrator.

2 -- Run the command:
dism /online /get-packages /format:table

3 -- Look at the bottom of the output for the line:
Package_for_RollupFix~31bf3856ad364e35~amd64~~26100.7623.1.20 | Installed | Security Update | 2026-01-14

It might also be: Package_for_RollupFix~31bf3856ad364e35~amd64~~26100.7623.1.10 , if so, use that value in the next command.

4 -- Run the command:
dism /online /remove-package /PackageName:Package_for_RollupFix~31bf3856ad364e35~amd64~~26100.7623.1.20
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10+ people found this answer helpful.
dmarti 0 Reputation points

2026-01-15T15:21:29.1666667+00:00

Thanks for sharing, this was definitely the cause and your resolution was spot on!

Rob Endter 5 Reputation points

2026-01-15T16:11:16.07+00:00

that isn't working either - get: error: 0x800f0825

Hornblower409 7,005 Reputation points

2026-01-15T16:23:14.75+00:00

@Rob Endter said

get: error: 0x800f0825

1 -- At what step (command) do you get the error?

2 -- After a Windows reboot, Settings -> Windows Update

Are there any pending updates?

3 -- Settings -> Windows Update -> Update History

Do you have a line: "2026-01 Security Update (KB5074109), Successfully installed"?

4 - From an Command Prompt as Administrator

dism /online /get-packages /format:table

Look at the bottom of the output. Do you have the line? Package_for_RollupFix~31bf3856ad364e35~amd64~~26100.7623.1.20 | Installed | Security Update |

5 -- Do you have a DISM log file at C:\Windows\Logs\DISM\dism.log ?

If so, what are the last few lines?

Hornblower409 7,005 Reputation points

2026-01-15T17:03:15.7866667+00:00

@Jim Cofer said

if you try uninstalling KB5074109 and get an error message, uninstall Windows Sandbox THEN try uninstalling the update

I have seen this suggestion from other sources as well. Might be work trying if the DISM command line uninstall fails and you can't pinpoint the cause from the DISM log file at C:\Windows\Logs\DISM\dism.log

How do I uninstall Windows Sandbox?

https://learn.microsoft.com/en-us/windows/security/application-security/application-isolation/windows-sandbox/windows-sandbox-faq#how-do-i-uninstall-windows-sandbox

Jim Cofer 25 Reputation points

2026-01-15T17:09:49.6666667+00:00

@Hornblower409 Or you can click WIN+R and type "optionalfeatures.exe" in the Run: box, and uncheck "Windows Sandbox". Reboot as instructed.

MUB 90 Reputation points

2026-01-15T17:35:46.4033333+00:00

This is the solution. I had to disable updates (for two weeks) before rebooting or it would just re-install the update, however this fix does correct the issue. Waiting now for a hotfix from MS so I can turn back on updating.

Bryan Delp 30 Reputation points

2026-01-16T12:29:47.29+00:00

This worked for me. I had to run the CMD prompt as an administrator: search for CMD, then right click on it and select run as an admin.

Jay Korobow 25 Reputation points

2026-01-16T21:13:23.39+00:00

i am not sure how or where to add comments. my last effort got me an azureDevops error. after reinstalling and repairing windows and office to no avail with my pop3 outlook client freezing, not loading profiles, not responding on various tasks (reply, open, go from inbox to sent) the problems comes and goes but mostly comes. 2 high techs at ms tried to help one kept getting errors uninstalling upd components and did exhaustive Offline / forced package removal using DISM and servicing stack commands to get it removed... seemed o at first, i tested numerous outlook client tasks while tech waited and all worked ok although there were false all-clear events earlier that were not at all ALL CLEAR. i said thx gave a 10star review got a case nbr was told contact us if reoccurs. sure enough minutes later it went awry again many issues. funny story using the case nbr i tried to contact ms support as instructed and reached voice prompt hell + 1. silly me asked grok for a "good" ms number to call to get a live person as i failed for hours... grok complied. haha grok gave me a scammer, who took advantage of me making believe they were high level support and when they asked for credit card stuff i asked for proof of id they hung up on me lol. i finally got to a 365 signin a contact support link where a legit agent called me back. new case nbr assigned. she said we know we know we are working on it (this was 2 days ago) check this link for progress byebye. she emailed me something which turns out is internal and tries to sign me in to internal azure team and all sorts of new errors and collateral damage occurred (i had grok review and explain, identify etc.) meanwhile its been 4 days since this hell began i cannot use my important critical outlook email client or find WHERE WE ARE FIXING IT in any reliable way except here, anywhere else? anyone know? advice. Sympathy? lol.

Jay Korobow 25 Reputation points

2026-01-16T21:18:27.0433333+00:00

chatgpt told me my comment above will get sympathy laughter and no real help, and told me to try this... TY in advance: I’m adding my experience in case it helps confirm scope or status.

Since the January Windows 11 security update (KB5074109), my Classic Outlook POP3 profile has become unstable: frequent freezes, “Not Responding,” failure to load profiles, and hangs when opening/replying/moving between folders.

I’ve done full Office repair/reinstall and Windows repair with no lasting improvement. Two Microsoft support engineers worked on this — one had to remove the update using offline/forced servicing stack remediation (DISM) because standard uninstall failed. Outlook appeared stable briefly, then relapsed minutes later.

Support acknowledged this as a known issue (internal bug reference given) and advised monitoring for a fix, but the tracking link provided routes to internal Azure DevOps, which consumer accounts cannot access.

At this point Outlook remains unusable for critical email. My questions: – Is there a public status page or known-issue article tied to this bug? – Are others with POP3 / Classic Outlook seeing the same behavior after KB5074109? – Any reliable workaround while Microsoft works on a fix?

Appreciate any confirmation or guidance.

Hornblower409 7,005 Reputation points

2026-01-16T22:07:24.4033333+00:00

@Jay Korobow said

Is there a public status page or known-issue article tied to this bug?

Classic Outlook POP account profiles hang and freeze after Windows 11 update to KB5074109
https://support.microsoft.com/en-us/office/classic-outlook-pop-account-profiles-hang-and-freeze-after-windows-11-update-to-kb5074109-590fe356-ecc2-49f4-b9e3-bd39fafa58f6

Are others with POP3 / Classic Outlook seeing the same behavior after KB5074109?

Yes. Everyone on this thread, similar reports on Reddit, and people all around the world.

Any reliable workaround while Microsoft works on a fix?

Uninstall KB5074109 and pause Windows Updates so it is not reapplied.

GFL4 75 Reputation points

2026-01-17T15:22:36.2533333+00:00

I am traveling for three months and working off a travel laptop so cant really test. So can someone do this please. Very easy to pause one drive.

Gerry Anderson 0 Reputation points

2026-01-17T21:17:58.0866667+00:00

I was about to execute the Run Command you suggested when I noticed a slight difference in the middle of the string of the installed update. The installed command that was installed on January 14 on my laptop had ~arm64~~, rather than ~amd64~~(bold letters were added in this note by me to highlight difference). I assume I would just substitute arm for amd in the remove command?

Hornblower409 7,005 Reputation points

2026-01-17T22:26:37.0066667+00:00

@Gerry Anderson said

my laptop had **arm64 rather than amd64. I assume I would just substitute arm for amd in the remove command?

I can not test, but yes, I would think that you use the arm64 package name. Whatever the dism /online /get-packages command shows as installed.

Please post your results for other ARM CPU users to see.

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Gerry Anderson 0 Reputation points

2026-01-17T23:15:36.4033333+00:00

I did substitute ARM for AMD as that was in the install command. I confirmed that my laptop had an ARM processor. The uninstall command started to process but failed, I received the same error code as another commentor, then tried to uninstall Windows Sandbox as suggested, however, Sandbox is not installed on my laptop. At a loss for next steps

Makapu 91,800 Reputation points Volunteer Moderator

2026-01-18T06:50:16.0866667+00:00

reports from Japanese forums confirm that this issue occurs when the Outlook Classic .pst data file is stored in OneDrive. If you are unable to uninstall KB5074109, please refer to the article below and move your data file to a local location to see whether this resolves the problem.

How to remove an Outlook .pst data file from OneDrive - Microsoft Support

Hornblower409 7,005 Reputation points

2026-01-18T13:22:34.34+00:00

@Gerry Anderson said

The [DISM] uninstall command ... failed ... Sandbox is not installed

Do you have a DISM log file at C:\Windows\Logs\DISM\dism.log ?
If so, what are the last few lines? Or does it have any details on the error?

GFL4 75 Reputation points

2026-01-18T16:12:23.8633333+00:00

Too many pst files to move. Wouldnt unhooking from one drive until fixed work?

Hornblower409 7,005 Reputation points

2026-01-18T18:17:43.9833333+00:00

@GFL4 said

Too many pst files to move. Wouldnt unhooking from one drive until fixed work?

If that question was directed to me - I don't know. I can't get my Outlook to fail, so I can't test.

@Gabe Bratton was the one asking for people to test the OneDrive interaction. You will have to wait for an answer from him.

Allen Mendelsohn 5 Reputation points

2026-01-19T12:52:39.6133333+00:00

Thank you @Hornblower409 !!!! Your instructions are 100% accurate and this has solved my Outlook issue.

Barb6110 0 Reputation points

2026-01-19T20:36:57.27+00:00

Thank you Hornblower409. Followed your steps (yup - I'm old school & "teethed" on Fortran & DOS - black & white screens don't intimidate me :)) & it worked! Back in business!

Bill P 10 Reputation points

2026-01-20T19:34:39.1+00:00

I had no problem using the regular update uninstallation process.

Uninstallation of KB5074109 is the quickest way to get Outlook functioning back. I simply used the uninstall update method provided in the Windows Update Tab in Settings. The sort of items for uninstallation is in reverse order of installation putting KB5074109 at the bottom and in some cases out of sight without scrolling. After reboot my computer hung for 10 minutes after which hit the reboot button and it proceeded normally. It is imperative that Windows Updates be paused until Microsoft announces a fix and/or OOB update.

Fred 5 Reputation points

2026-01-21T07:41:26.7566667+00:00

This actually worked for me. Thanks!!
The only odd thing is, that KB5074109 is still listed among the "installed updates".

Hornblower409 7,005 Reputation points

2026-01-21T13:58:14.0633333+00:00

@Fred said

The only odd thing is, that KB5074109 is still listed among the "installed updates".

Not sure where you are looking. Full menu path you are using to see "installed updates", or a screen shot would be helpful.

Depending on how you did your uninstall, it may still be listed at:
Settings -> Windows Update -> Update History

But none of the uninstall methods I have used leave it showing at:
Settings -> Windows Update -> Update History -> Related settings -> Uninstall updates

Fred 5 Reputation points

2026-01-21T14:24:27.6033333+00:00

There you go, @Hornblower409

Hornblower409 7,005 Reputation points

2026-01-21T14:48:58.7566667+00:00

@Fred said

Updateverlauf

= Update history ?

Depending on how you did your uninstall, it may still be listed at:
Settings -> Windows Update -> Update History

Dan Worrells 0 Reputation points

2026-01-22T16:02:42.5333333+00:00

Thank you so much! The Microsoft instructions were unusable. I only wish I had seen your instructions a few long, frustrating days ago.

Roy Ong 0 Reputation points

2026-01-23T15:32:42.5866667+00:00

I was unable to uninstall KB5074109 until I come across this post. Above 4 simple steps solved my issues without any side-effect (so far). Many thanks!!

Hornblower409 7,005 Reputation points

2026-01-23T15:42:51.4633333+00:00

@Roy Ong said

[DISM command line uninstall] solved my issues without any side-effect (so far)

Don't forget to Pause your Windows Updates or it will try to re-install KB5074109 again.

How to Pause Windows Updates
https://support.microsoft.com/en-us/windows/pause-updates-in-windows-643e9ea7-3cf6-7da6-a25c-95d4f7f099fe

And monitor the official Support page for this issue to know when it is safe to resume Windows Updates.

https://support.microsoft.com/en-us/office/classic-outlook-pop-account-profiles-hang-and-freeze-after-windows-11-update-to-kb5074109-590fe356-ecc2-49f4-b9e3-bd39fafa58f6

LB 0 Reputation points

2026-01-24T14:14:32.4666667+00:00

Receiving error message: The filename, directory name, or volume label syntax is incorrect.

C:\Windows\System32>/PackageName:Package_for_RollupFix~31bf3856ad364e35~amd64~~26100.7623.1.20

The filename, directory name, or volume label syntax is incorrect.

Any recommendations?

Hornblower409 7,005 Reputation points

2026-01-24T15:26:39.2166667+00:00

@LB said> [Command Line] Receiving error message: The filename, directory name, or volume label syntax is incorrect.

If you get any kind of error trying to use a command line to uninstall KB5074109 - I would suggest you STOP and do not try any other commands. You could seriously damage your installed software.

Either:

Try the other workaround - Move any PST/OST files out of your OneDrive folder and use ScanPST to check for errors.

How to remove an Outlook .pst data file from OneDrive https://support.microsoft.com/en-us/office/how-to-remove-an-outlook-pst-data-file-from-onedrive-b6b9e522-59bd-40f7-949f-168d0aa9b38e ScanPST https://learn.microsoft.com/en-us/troubleshoot/outlook/data-files/how-to-repair-personal-folder-file Once you have moved all of your PST/OST files KB5074109 won't break your Outlook.

Or contact Microsoft Support and ask "How to uninstall KB5074109?"
https://support.microsoft.com
Mike Chern 85 Reputation points

2026-01-16T07:24:03.5833333+00:00

I have Office 2021 and use Outlook client for e-mail. I have POP3 account setting in my profiles and they have worked for years. As soon as the January 14th update was issued, Outlook started freezing and crashing. I uninstalled KB5074109 and now Outllook works fine again. No repairs or fixes listed worked except uninstalling the security update. I had to postpone updates to keep it from reinstalling. It's the only way I could make Outlook work. The security update KB5074109 is the culprit. I am running Windows 11.
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10+ people found this answer helpful.
Ricardo Milton Cunha 0 Reputation points

2026-01-16T15:39:07.27+00:00

Exactly same here and after uninstall that security update, Outlook was back working normally as always!

Chris Hadley 10 Reputation points

2026-01-16T17:23:27.43+00:00

Mike, you are not alone on this. Done similar and await a solution.

Tony 10 Reputation points

2026-01-16T20:13:57.18+00:00

Same with me - two wasted days of uninstalling and reinstalling Outlook

Istor 0 Reputation points

2026-01-19T09:19:31.5933333+00:00

Same Here. I just uninstalled KB5074109 and my Outlook is back to normal. I had a very frustrating time for 3 working days!! totally unacceptable!

John Macers 0 Reputation points

2026-01-19T23:32:12.2666667+00:00

I uninstalled which fixed the problem. Question is how does MS manage to screw up so offern?

TamakoTakamatsu-6777 10 Reputation points

2026-01-20T02:45:34.5233333+00:00

I tried uninstalling the update, but then got nervous about the purported security risks, so I installed it again---and of course I cannot really use my Outlook (classic). Are others worried at all about the security risks? Would be grateful for any comments...

Mirka Breen 55 Reputation points

2026-01-20T03:36:51.14+00:00

Yes, @Tamako Takamatsu, I am worried, but a non-working email is not an option. It's essential to have email. It is for most of us the MAIN reason for using a computer. I will remain without the defective update until it is fixed and working with Outlook Classic no matter what. Like thousands (or is it millions?) I am waiting for Microsoft engineers to come back with a fix and give us a fully functional product.

Steve Rymell 0 Reputation points

2026-01-21T23:25:06.76+00:00

uninstalled the update after my Outlook kept freezing up.

This resolved the problem until the update was downloaded again so now i need to uninstall and stop automatic patching.

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Pam Howard 10 Reputation points

2026-01-22T17:17:51.4466667+00:00

Did not work for me and my email keeps installing the same emails each time I have to re-open Outlook after it crashes....so I get all emails from Jan 15 thru today again and again....

Hornblower409 7,005 Reputation points

2026-01-22T17:35:35.58+00:00

@Pam Howard said

Did not work for me and my email keeps installing the same emails each time I have to re-open Outlook after it crashes

Which of the two workarounds have you tried?

1 -- Move any PST files out of your OneDrive folder and use ScanPST to check for errors.

How to remove an Outlook .pst data file from OneDrive
https://support.microsoft.com/en-us/office/how-to-remove-an-outlook-pst-data-file-from-onedrive-b6b9e522-59bd-40f7-949f-168d0aa9b38e

ScanPST
https://learn.microsoft.com/en-us/troubleshoot/outlook/data-files/how-to-repair-personal-folder-file

2 -- Uninstall the Jan 2026 Update KB5074109 and Pause Windows Updates.

How to uninstall a Windows Update
https://support.microsoft.com/en-us/windows/how-to-uninstall-a-windows-update-c77b8f9b-e4dc-4e9f-a803-fdec12e59fb0

Pause Windows Updates
https://support.microsoft.com/en-us/windows/pause-updates-in-windows-643e9ea7-3cf6-7da6-a25c-95d4f7f099fe

If you can not uninstall KB5074109 thru normal means contact Microsoft Support and ask "How to uninstall KB5074109?"
https://support.microsoft.com
Q&A Assist

2026-01-14T12:21:41.68+00:00

AI generated content. This question contains an answer created with AI from Q&A Assist. Learn more
It appears that the issues you are experiencing with Outlook Classic after the January 2026 security update (KB5074109) may be related to known problems that can occur after updates. Here are some steps you can take to troubleshoot and potentially resolve these issues:
1. Check for Additional Updates: Ensure that you have installed all available updates for Outlook and Windows. Sometimes subsequent updates can fix issues introduced by previous ones.
2. Repair Outlook: You can try repairing your Office installation. To do this, go to Control Panel > Programs > Programs and Features, select Microsoft Office, and then choose the Repair option.
3. Disable Add-ins: Sometimes, add-ins can cause Outlook to behave unexpectedly. You can start Outlook in safe mode (hold down the Ctrl key while starting Outlook) to see if it opens without issues. If it does, consider disabling add-ins one by one to identify the culprit.
4. Check Email Account Settings: Since you mentioned using a Yahoo POP account, ensure that your account settings are correctly configured. Verify that the settings for saving sent items are enabled in your account configuration.
5. Uninstall the Update: If the above steps do not resolve the issue, you may consider uninstalling the update. To do this, go to Control Panel > Programs > Programs and Features, select View installed updates, find the KB5074109 update, and choose to uninstall it.
6. Contact Support: If the problem persists, consider reaching out to Microsoft Support for further assistance, especially if the issues are directly related to the update.
These steps should help you troubleshoot the problems with Outlook Classic. If you need more specific guidance on any of the steps, feel free to ask!

References:
- Outlook not responding error or Outlook freezes when you open a file or send mail
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4 people found this answer helpful.
Chris Seagrave 345 Reputation points

2026-01-14T20:17:20.3233333+00:00

Tried points 1 to 4 and they didn't solve the issue. I went Settings > Windows Update > Update History > Uninstall Update and KB5074109 wasn't an option to uninstall.

Simon Thomas 55 Reputation points

2026-01-14T21:43:05.16+00:00

Still remains a problem with Outlook freezing and crashing.

Gabe Bratton 686 Reputation points Microsoft Employee Moderator

2026-01-14T22:17:39.2733333+00:00

Simon,

Please check if you see any crash events for Outlook and share those. Go to the Windows Start button, Search, and type Event Viewer and open it. Click Windows Logs, Application Log. Look for Event 1000 for Outlook and if you find one find the corresponding Event 1001 Windows Error Reporting and share that event. If you only find Event 1000 please share that. If you don't find either of those see if you find any hang events and share those. Sometimes there are not exact matching events but if there are it could help assess the issue. It can also help confirm if others are having the same crash type issue.

S A W 0 Reputation points

2026-01-15T04:36:46.51+00:00

I had the same problem. I was able to Uninstall the Security Update, following the instructions, and the system and Outlook appears to be working OK. Hope this works for you.

Chris Seagrave 345 Reputation points

2026-01-15T12:10:20.2866667+00:00

Points 1-4 make no difference, couldn't do point 5 as there was no uninstall option. Point 6 went to my local Computer repair shop and they advised I do a System Restore from before the 2026-01 Security Update (KB5074109) (26200.7623) was installed, which has worked so far.

Tony 0 Reputation points

2026-01-15T12:12:56.2133333+00:00

I Uninstalled the update KB5074109 and after that my problems are gone.

Dave 0 Reputation points

2026-01-18T11:46:12.4833333+00:00

It looks like the new update January 17-18 fixed issue

Hornblower409 7,005 Reputation points

2026-01-18T13:54:54.6166667+00:00

@Dave said

It looks like the new update January 17-18 fixed issue

If I do "Check for Updates", I do not see any additional major updates after January 13 KB5074109.

I also do not see any update to the Support Article on this issue since January 15. And it still shows the status as INVESTIGATING.
https://support.microsoft.com/en-us/office/classic-outlook-pop-account-profiles-hang-and-freeze-after-windows-11-update-to-kb5074109-590fe356-ecc2-49f4-b9e3-bd39fafa58f6

Are you referring to the Out-of-band KB5077744 ?

Release Date: 1/17/2026
https://support.microsoft.com/en-us/topic/january-17-2026-kb5077744-os-builds-26200-7627-and-26100-7627-out-of-band-27015658-9686-4467-ab5f-d713b617e3e4

If so, I do not see anything in the KB Article that would indicate it is a fix for the Outlook Classic POP issue.

Could you please cite an official Microsoft source for your statement?

Or is this from personal experience?

i.e. You had the Outlook Classic POP issue, did not uninstall KB5074109, and installing KB5077744 fixed it for you?

S P 0 Reputation points

2026-01-20T21:56:18.1233333+00:00

Gleiche Antwort bekommen, alles durchgespielt, nichts geholfen. Nur eine Komplettwiederherstellung nach 6 Stunden vergeblicher Versuche. Effizienz für den Alltag gleich....0!

Bill P 10 Reputation points

2026-01-21T17:40:12.4566667+00:00

Uninstalling KB5074109 should be the first thing to do when the update crashes Outlook while doing NOTHING to Outlook before the uninstall.

Looking for the update to uninstall I did not see it at first ... after futzing with Outlook a million ways, repair, reinstall, new profiles, all sorts of different issues showed up, reported and unreported including an inability to log in... I went back and noticed that the sort of updates available to uninstall was the oldest at the top and the newest at the bottom ... then I scrolled and there was the offending KB5074109 at the BOTTOM of the list. Uninstalled it, the system went black on reboot (a known issue} rebooted again after waiting 10 or so minutes and Windows started and Outlook performed as though nothing happened.

Hornblower409 7,005 Reputation points

2026-01-21T17:49:39.1333333+00:00

@Bill P

Just a reminder - After uninstalling KB5074109 be sure to Pause Windows Updates or it will try to install it again.

https://support.microsoft.com/en-us/windows/pause-updates-in-windows-643e9ea7-3cf6-7da6-a25c-95d4f7f099fe

GFL4 75 Reputation points

2026-01-21T18:20:36.2433333+00:00

Why not use showhide to permanently pause this update

Hornblower409 7,005 Reputation points

2026-01-21T18:51:43.2433333+00:00

@GFL4 said

Why not use showhide to permanently pause this update

I assume you are talking about wushowhide.diagcab ?

If so, this tool (and all of the MSDT Troubleshooters) have been deprecated and are scheduled for retirement.
https://support.microsoft.com/en-gb/windows/deprecation-of-microsoft-support-diagnostic-tool-msdt-and-msdt-troubleshooters-0c5ac9a2-1600-4539-b9d0-069e71f9040a

Although I have used wushowhide under Windows 11 successfully, there are numerous reports of it's operation being "flaky" at best.

And then there is the problem that many people forget to unhide an update once the danger has passed and never get a potentially important update.

If anyone wants to try their luck, a search for wushowhide.diagcab should get you an old Microsoft downloads link.

Proceed at your own risk.

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Outlook Classic not opening properly or recording sent mails after 2026-01 Security Update (KB5074109) (26200.7623)

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