Microsoft Offers Workaround to Fix Bug Causing Classic Outlook to Crash at Startup

Key Takeaways:

• Microsoft has cofirmed that a bug in the classic Outlook for Windows (version 2407 or higher) is causing the app to crash during startup or in Safe Mode.
• The company has provided a workaround that to address this problem until a permanent fix is released.
• Microsoft has also acknowledged a separate issue preventing classic Outlook users from signing in or adding Gmail accounts.

Microsoft is working to fix a critical bug that causes the classic Outlook for Windows to crash during startup or when launching in Safe Mode. The company detailed in a support document that this issue affects users running version 2407 (Build 17830.20138 or higher).

Microsoft advises users to check if they’re affected by this issue by looking for crash Event 1000 or Event 1001 in the Windows Event Viewer Application Log. Several users reported that this problem specifically impacts Office 365 accounts and cannot be resolved by reverting to an earlier build.

“After updating to Version 2407 Build 17830.20138 or higher you find that Outlook may unexpectedly close at start up. Outlook will also close if you test in Safe Mode,” Microsoft explained. “This issue has been found to occur if the server-based rules for the M365 email account are corrupted or that Outlook cannot process.”

Workaround to fix Outlook startup crashes

Microsoft is working on an update to fix the bug, which will be released to customers in the coming weeks. In the meantime, the company has provided a temporary workaround that involves manually deleting all email rules associated with affected accounts. To do this, Outlook users will need to follow these steps:

• Run the Clean rules command line to delete the client and server rules by closing the Outlook app. Now, right-click the Windows Start button, click Run, and then paste the following command in the Run box paste: Outlook.exe /cleanrules.
• Click the Ok button.
• Create a new Profile by holding the Shift key when starting classic Outlook (if needed). In the Profile Picker dialog, select Options >> New, type a name for the new Outlook Profile, and then click OK.
• In the add account dialog, add one or more email accounts to include in the profile.

In other Outlook-related news, Microsoft has also acknowledged an issue that was preventing classic Outlook users from signing in or adding Gmail accounts. The company has released a fix for Office Insiders that changes the sign-in process to open another browser window.