Multiple users experiencing Outlook 365 freezes/white screen

Question

Multiple users experiencing Outlook 365 freezes/white screen

Scott Gray 96

We have multiple Outlook 365 users experiencing freezes/white screen from 10 seconds to 5 minutes or more when using a large shared user mailbox. Users are configured with personal user mailbox and secondary user mailbox (50Gb in size) which is not cached. In Place backup is enabled for the second mailbox. Second user/mailbox is assigned E3 licence. This specific team uses the secondary mailbox to triage and manage many incoming emails with attachments and they need to coordinate with each other and move mail items into sub folders based on region or job type. The mailbox is in online only mode because caching not only requires a huge OST and takes a long time to download on new installs but also results in delays between users when items are moved, flagged or categorised.

I have tried the following none of which has made a difference to performance with users :

Creating a new Outlook profile
Running Outlook in Safe mode to eliminate plugins
Disabled web plugins when outside of Safe mode
Disabling Anti-virus (Webroot SecureAnywhere)
Enabling cached mode for the secondary mailbox and setting retention to 3 months
Applying all windows updates and Office 365 updates
Running continuous ping in PingPlotter to determine any connectivity issues (none identified)
Disabling graphics hardware acceleration
Disabling “Optional connected experiences”
Running SARA/Outlook diagnostic tool – Nothing obvious or critical identified from what I can see
Checking AutoDiscovery settings - Nothing obvious or critical identified from what I can see
Contacting Outlook support via Outlook Help menu (zero luck there)
Checking Outlook connection status (control right click on Outlook icon > Connection status) for errors (none) and reconnecting when locked up - No effect, doesn't brink Outlook back
Tweaking NIC settings to disable low power mode etc

The only suggestions from Outlook support were that users should be using a shared mailbox instead of a user mailbox but I cant see how this would make any difference at all to connectivity to ExO. They recommend caching user mailboxes and un-caching shared mailboxes or at the least disabling download of shared folders – We already have the secondary mailbox in online only mode.

While this group of users are the main ones affected there are others in the organisation that have freezes too and they aren't using the same secondary mailboxes. It seems to affect users which have a shared mailbox delegated to them or access a mailbox in online only mode.

Other than reducing the mailbox size which seems to be the usual advice, is there anything you can suggest to test connectivity or determine what is causing the Outlook freeze?

Daniel 1 Reputation point

2021-02-17T00:40:37.557+00:00

I have the same issue with frequent freezes on a number of different computers and so far been unable to resolve, I suspect this is a widespread problem.
Brian Coyne 1 Reputation point

2022-04-20T00:48:13.307+00:00

Any resolution here from anyone? Same thing for us with about 5 shared mailboxes
David Jones 101 Reputation points

2022-04-20T02:08:10.3+00:00

For us it was a whole bunch of issues with Outlook, slowing down, freezing and even disconnecting or failing to connect shared mailboxes. Turned out to be Outlook failing to handle updating an Autodiscover reg key value, following a mailbox migration (in this case it was a mailbox defederation migration from GoDaddy MS 365 to Microsoft direct MS 365). The below article fixed the issues for us, despite the fact their symptoms description doesn't quite match. I was eventually pointed to this article after several days of troubleshooting with MS L2 support. I think the key take away for me is that Autodiscover failures can cause this kind of abhorrent behaviour, even if it's something as simple as your clients using a stale DNS record for the Autodiscover hostname (for which I've seen other posts about):
https://learn.microsoft.com/en-us/outlook/troubleshoot/profiles-and-accounts/cannot-connect-web-service-not-working-migrated-to-office-365

10 answers

Your answer

Daniel 1 Reputation point

2021-02-17T00:40:37.557+00:00

I have the same issue with frequent freezes on a number of different computers and so far been unable to resolve, I suspect this is a widespread problem.
Brian Coyne 1 Reputation point

2022-04-20T00:48:13.307+00:00

Any resolution here from anyone? Same thing for us with about 5 shared mailboxes
David Jones 101 Reputation points

2022-04-20T02:08:10.3+00:00

For us it was a whole bunch of issues with Outlook, slowing down, freezing and even disconnecting or failing to connect shared mailboxes. Turned out to be Outlook failing to handle updating an Autodiscover reg key value, following a mailbox migration (in this case it was a mailbox defederation migration from GoDaddy MS 365 to Microsoft direct MS 365). The below article fixed the issues for us, despite the fact their symptoms description doesn't quite match. I was eventually pointed to this article after several days of troubleshooting with MS L2 support. I think the key take away for me is that Autodiscover failures can cause this kind of abhorrent behaviour, even if it's something as simple as your clients using a stale DNS record for the Autodiscover hostname (for which I've seen other posts about):
https://learn.microsoft.com/en-us/outlook/troubleshoot/profiles-and-accounts/cannot-connect-web-service-not-working-migrated-to-office-365

Answer 1

Hi there,

I'm facing the same problem since September 2020 on a specific shared mailbox. Of course there are some additional shared folders for different departments but the problem there is smaller.

All of the machines are identical, same software installed, brand new machines (i7, 16GB RAM, SSD etc.)
The shared mailbox is accessible to about 13 users. Users make use of their user mailbox, the corresponding in-place Archive one, the shared mailbox in question and perhaps an additional shared mailbox which is very small.
They complain that 3-4 times a day the get "Not responding" for about 10 seconds or for ever until they restart Outlook.
There's only one machine on the same department which have no issues at all although the .ost file is about 48GB! :D We've cross checked that machine with the rest of the other ones, but there's nothing special on that. The only difference is that this user doesn't work so much on the shared mailboxes.

Things i have tried so far:

Disabled “Hardware Acceleration” in Outlook. Installed the latest graphics card drivers.
Cleaned up the big shared mailbox and left only 1 year’s emails (new total size: ~17GB) (In-place archive is disabled)
Created new Outlook profiles
Opened Outlook in safe mode
Limit Outlook caching to 6 months (with creation of a new profile again) in order to keep .ost files small (although all of the client machines are brand new and fast).
Completely uninstalled the Kaspersky AV.
Repaired Office.
Tried the 64bit version.
Checked the company’s firewall.
On the shared mailbox, we've tried to split up a 15GB top level folder to smaller ones.
Installed Office suite on a brand new pc without any additional software
Tried to create a new O365 user on the brand new pc
Disabled cached exchange mode but of course the problem got bigger :)
Ran O365 network connectivity tests, made the some changes to our DNS servers which resulted to Location assessment: ‎89‎% (178/200 points)
We've contacted Microsoft's O365 support but the problem is out of their scope as they clearly said.

Additional Notes:
* We're using O365 Business Standard
* The internet connection is fast enough and usually is ~30-40% occupied with a low number of concurrent sessions.
* LAN is Gigabit
* We make use of other shared mailboxes on different departments without issues (i must say that these mailboxes have fewer messages in total)
* Outlook on the web do not have any problems. The problem resides on the desktop version
* The "Not Responding" issue usually happens when the user tries to search an email on the shared mailboxes, or jump from one email to another, or move an email to another mailbox.

Answer 2

Scott Gray 96

Hi @Thanasis TaN

I've not yet resolved this issue and my users are still experiencing lock ups on a daily basis. They've just been closing Outlook and re-opening to speed up the process (instead of waiting 5 mins to indefinitely for it to come good). Since I started this thread we've upgraded to Gigabit internet at the office too and that doesn't seem to have helped things.

We are still running the shared mailbox entirely in online only mode (user mailbox is cached but not the shared ones).

Surprised there is no diagnosis MS can do to assist TBA.

Please let me know if you have any luck on your end.

Thanks,

Scott

Thanasis TaN 1 Reputation point

2021-02-05T08:35:39.953+00:00

Hi Scott,

Too pity that you're still having problems.. Still nothing here as well.
May i ask what kind of firewall do you use?
Scott Gray 96 Reputation points

2021-02-08T23:52:37.493+00:00

We have Cisco ASA firewalls.

HP desktop PCs and HP and Toshiba laptops.

The HP desktops appear to be the ones affected however that could be coincidental as the staff with the shared mailbox are setup in a call centre type scenario and don't require laptops. At one stage I suspected an HP QoS application but nothing changed when I removed it from one of the problem PCs.

I have recently tried changing MTU of the ethernet adapter to < 1500 to see if there is packets dropped by firewalls but this hasn't helped (not at 1454 anyway).

I have also disabled Microsoft Store apps auto updating and apps running in the background to see if that makes any difference. Bizarre that MS has no answers when it seems to only affect the Outlook application and it seems many others have similar issues.

Let me know if think of anything else.

Answer 3

Thanasis TaN 1

Hey Scott, still nothing here.
May i ask if you have a dual wan or an SD-wan on your firewall?

Scott Gray 96 Reputation points

2021-02-24T00:48:01.643+00:00

Not sure. I'll get back to you about this.

I was also going to instigate DPI settings. I found the following which is not related to our firewall but thought it interesting:

https://www.sonicwall.com/support/knowledge-base/connection-issues-for-microsoft-skype-office365-after-enabling-dpi-services/170505477596414/

Something for you to try perhaps.
Thanasis TaN 1 Reputation point

2021-02-26T10:28:49.03+00:00

Hey Scott,

On my firewall the DPI takes place on IPS engine but I think that if that's the problem i would have the same problems on personal mailboxes as well (those who don't make use of shared mailboxes).
Never the less, I 'll check it out.

For the moment I'm testing the possibility of the dual WAN being responsible, so I'm getting the traffic of the affected users destined to Microsoft services to pass through the WAN1.

On Tuesday I'm planning to enable Offline Mode on a user's Outlook (and let him do stuff on the shared mailbox) to see if this is a connectivity problem or not.

I'll keep in touch.
Thanasis TaN 1 Reputation point

2021-03-02T09:33:46.77+00:00

Single WAN doesn't seem to solve the problem.. outlook still hangs.
Scott Gray 96 Reputation points

2021-03-03T03:00:52.57+00:00

Hey mate,

We don't use dual or SD WAN on our side. Found an option in our firewall to force max segment size for TCP connections to be x and have disabled it. Will let you know if that improves things.

Thanks for keeping up the updates.
Thanasis TaN 1 Reputation point

2021-03-03T12:21:11.06+00:00

Getting Outlook to Offline mode shows that there are no problems during a 1 day period. That's seems logical cause the mailbox do not get any updates while offline.
Thanasis TaN 1 Reputation point

2022-09-29T13:57:40.12+00:00

Hey there!
Since the day we made some changes to the DNS resolution taking place on users' machines, the problems disappeared.
We're using 2 WANs from 2 different ISPs, so for DNS traffic going through WAN1 we're resolving with ISP#1's DNS servers while for WAN2 DNS traffic we're resolving with ISP#2's DNS servers. Since that day nobody experienced any delays on the shared mailboxes.

Good luck to everyone!

Answer 4

David Jones 101

Hi guys, We are experiencing this issue also. Has there been any progress on a resolution or work around, since March, please?

One thing I have noticed is that the Windows Resource Monitor seems to list several processes as "Suspended" along with the "Not Responding" OUTLOOK.EXE process. I'm beginning to wonder if this is Outfook causing locking itself up, perhaps something to do with search indexing, via SearchApp and the second OUTLOOK.EXE, that is in a "Suspended" state. Here's a screen dump of what I'm seeing...

Thanasis TaN 1 Reputation point

2021-11-22T11:21:14.313+00:00

Hi there!

Nothing yet, although users don't bother us anymore about the specific problem.. don't know if the problem is resolved or they just gave up :)
Our last try was creating 2 rules for the 2 WANs regarding to the name resolutions. That is, one rule for traffic going through WAN1 using the corresponding ISP's name servers and another one for WAN2.

Answer 5

Hope Emmanuel Ohiembor 1

I had the same issue and in my own case, I have two Microsoft 365 email accounts and two shared mailboxes connected to the Outlook 365. When I observed the outlook was freezing all the time, I disabled cache mode on the two shared mailboxes leaving only my two personal mailboxes in cache mode and the freezing stopped.

You can try this and let me know if it works for you.

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Multiple users experiencing Outlook 365 freezes/white screen

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