Classic Outlook crashes and opens in Safe Mode starting March 12 2026

Last Updated: March 17, 2026

ISSUE

Starting around March 12, 2026, classic Outlook might crash and then prompt to start in Safe Mode. This issue is happening when older builds of classic Outlook are using the newest version of the Teams Meeting Add-In build 1.0.26026.3.

classic Outlook safe mode error

The Event Viewer Application Log, Event 1000 crash event:

Faulting application name: OUTLOOK.EXE, version: 16.0.16924.20150, time stamp: 0x654eea05 Faulting module name: MSVCP140.dll, version: 14.32.31332.0, time stamp: 0x8b64702c Exception code: 0xc0000005 Fault offset: 0x00000000000132f8 Faulting process id: 0x6E64 Faulting application start time: 0x1DCB63FAA284D4E Faulting application path: C:\Program Files\Microsoft Office\root\Office16\OUTLOOK.EXE Faulting module path: C:\Program Files\Microsoft Office\root\Office16\MSVCP140.dll

STATUS: DESIGN LIMITATION

This issue was originally investigated as Microsoft 365 incident EX1254044. Users may be unable to use classic Outlook while the Microsoft Teams Meeting Add-in is enabled.

WORKAROUND

If you need to check the Office build open Word or start Outlook in Safe Mode by holding down the Ctrl key when you start Outlook.

Update Office to the latest build.
1. Follow the guidance in How to update Microsoft 365 or Office for Windows to update Office. Since Outlook is crashing, open Word and select File > Account > Update Options > Update Now.
2. For information about how to check what build of Office you are using, please go to About Office: What version of Office am I using?
3. To check the latest builds by Microsoft 365 Office Channel, please go to Update history for Microsoft 365 Apps (listed by date).
As a workaround, you can also perform an Online Repair of Office. For more information, please go to Repair an Office application.
Temporarily disable the Teams Meeting Add-in if you need to stay on the older build of Office you are using.
1. Open Outlook in Safe Mode. To do this hold down the Ctrl key when you start the application or please go to Open Outlook in safe mode and follow the steps.
2. Select File > Options > Add-ins > Go.
3. On the COM Add-ins dialog, uncheck Microsoft Teams Meeting Add-in for Microsoft Office and select OK.
4. Restart Outlook.