Outlook Classic Stuck on Loading Profile

Question

Outlook Classic will not open normally. Loading Profile is displayed for however long the application remains open.

Initially I thought this was potentially related to the Teams Add-In issue from this month, so I tried to open Outlook Classic in safe mode. Upon using the usual profile, the issue reoccurs.

I tried to create a new profile, and entered the user's 365 email address, but this refused to add, displaying an error.

Among the options is Troubleshoot, which when clicked opened an Outlook Classic instance that was not signed in and displayed nothing in the inboxes.

Because I managed to access the application, I proceeded to disable all of the add-ins present, and tried to load again. The issue reoccurred, both normally and in Safe Mode.

I also checked for updates while the application was open, which suggested it is fully up to date.

I am unable to repair the application, as it does not appear under Installed Apps.

I have gone through the process of reinstalling Office Applications, this has not fixed the error.

I have located and deleted the .ost files, as well as deleted the profiles present when opened in Safe Mode. This was to force a fresh profile and .ost creation, but it just continued to reproduce the same errors as before.

I tried to use the older style of profile addition within Outlook, but this just suggested no encrypted or unencrypted connection to the mail server was possible. This may potentially be the root cause.

This issue has appeared on two devices within the org, with the same steps and errors reoccurring. I have tried to run SFC and DISM scans, checked for Windows and device provider specific updates, and have pinged Outlook and Exchange services with no issues.

Answer 1

*This is a user-to-user support forum. Moderators and contributors, including Microsoft employees participating externally, cannot directly intervene in Microsoft product features or access back-end systems. Our role is limited to providing technical guidance on reported issues, requests, or ideas based on our practical experience.

Hi @Harry Stenson

I understand that Outlook Classic is perpetually stuck on the "Loading Profile" screen. You have done an incredibly thorough job testing all the standard fixes: trying Safe Mode, disabling add-ins, deleting .ost files, clearing out old profiles, running SFC/DISM scans, and even completely reinstalling the Office applications. The critical clue you uncovered is the error received during the older profile setup method, which stated that neither an encrypted nor unencrypted connection to the mail server is possible. This definitely seems to point to the root cause.

Since you have practically exhausted every local troubleshooting method, there is only one local variable left to test. If you haven't already, please try creating a completely new Windows User Profile on one of the affected machines, log into that fresh Windows environment, and see if Outlook can successfully connect and build a profile there.

If the issue persists even on a fresh Windows profile, this strongly indicates a deeper tenant-level or backend routing issue that goes beyond local client software. At that stage, please reach out to your IT Admin. If you are the Microsoft 365 Administrator, I highly recommend raising a support ticket directly through the Microsoft 365 Admin Center so the advanced backend support team can investigate the server-side connection logs.

You can refer to this article for guidance on opening a ticket:

Get support - Microsoft 365 admin | Microsoft Learn

Thank you for your patience and for sharing such a detailed breakdown of your troubleshooting steps. I hope the advanced support team can get this connection issue resolved for you quickly!

---

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Answer 2

Based on the behavior described (classic Outlook stuck on “Loading Profile”, crashes or will not start even in Safe Mode, and issues persisting after profile/OST recreation and reinstall), the next supported steps are:

1. Start Outlook in Safe Mode and disable add-ins
   • From Windows, run: Outlook.exe /safe.
   • If Outlook opens, go to File > Options > Add‑ins.
   • At Manage: COM Add‑ins, select Go, clear all check boxes, and select OK.
   • Close Outlook and start it normally.
   • If Outlook works, re‑enable add‑ins one by one, restarting Outlook each time, until the problematic add‑in is identified.
2. Repair or recreate the Outlook profile
   • A corrupted profile can cause Outlook to hang at “Loading Profile” or fail to open mail folders.
   • Create a new profile from Control Panel > Mail > Show Profiles > Add and add the user’s account there.
   • In the Show Profiles dialog, select Prompt for a profile to be used and start Outlook with the new profile.
   • If Outlook now opens and works, the original profile is corrupted and can be removed after any needed data is backed up. When removing a profile, all offline cached content (.ost) for that profile is deleted, so ensure any needed data is on the server or exported first.
3. Repair Outlook data files if specific folders cannot be opened
   • If Outlook shows errors such as “This set of folders could not be opened” when it does start, run the Inbox Repair Tool (scanpst.exe) against the affected .pst/.ost file as documented in Repair Outlook Data Files (.pst and .ost).
4. Check for known crash condition with ucrtbase.dll (if Outlook closes at startup)
   • If Event Viewer shows Outlook crashing at startup with faulting module ucrtbase.dll on Outlook for Microsoft 365 Version 2407 Build 17830.20138 or higher, clear corrupted rules and recreate the profile:
     1. Close Outlook.
     2. Run Outlook.exe /cleanrules from Run.
     3. Create a new Outlook profile if needed.
     4. If the issue persists, remove any remaining rules in Outlook on the web at the mailbox’s Mail > Rules page.
5. If Outlook is frozen but not crashing
   • Confirm no background process is blocking Outlook (for example, auto‑archive or large send/receive) by checking the status bar at the bottom of the Outlook window when it is responsive.
   • If Outlook is completely frozen and none of the above steps help, follow the guidance in Classic Outlook not responding, stuck at "Processing," stopped working, or freezes to create and switch to a new user profile at the Windows level via Control Panel > Mail > Show Profiles.

If, after these steps, Outlook still cannot complete profile creation for multiple users, collect crash details from Event Viewer (especially for ucrtbase.dll) and proceed with the rules cleanup and profile recreation workaround, as this is a documented cause of startup failures in current Outlook builds.

---

References:

• Troubleshoot Outlook for Windows issues
• Classic Outlook not responding, stuck at "Processing," stopped working, or freezes
• I can’t start Microsoft Outlook or receive the error “Cannot start Microsoft Outlook. Cannot open the Outlook Window”
• Classic Outlook unexpectedly closes at start up on faulting module ucrtbase.dll