[German]Microsoft is currently investigating a reported issue with Outlook Classic. There are user reports that using the Microsoft Teams Meeting add-in causes the Outlook Classic client to crash or become unusable.
Discussion on reddit.com
I found a discussion on reddit.com titled Führt das aktuelle Teams Outlook Add-In zu Abstürzen mit Office 2021? (Does the current Teams Outlook add-in cause crashes with Office 2021?) dated March 16, 2026. One user writes there that users with the current Teams version 26043.2016.4478.2773 are encountering the problem that Outlook (Classic) crashes on startup. If the Microsoft Teams add-in is disabled, these crashes stop.
Users with older versions of the Teams client don't experience this crash issue either, the thread starter writes. In the poster's environment, Microsoft Office 2021 is running on Windows 11. The thread starter asks if anyone else has observed this behavior or knows of a fix.
Other affected users confirm the problem, and one user attributes it to the runtime libraries. He outlines a workaround for this:
- The dotnet-runtime-6.0.36-win-x86.exe file was installed (since Office 2019 LTSC 32-bit is being used).
In addition, the VC Redistributable Runtime 14.50.35719.0 was installed.
After restarting the Outlook Classic client, both the client and the Teams plugin are working again. Some affected users confirm that this helped. It is reported that the VC Redistributable version 14.40 and higher appears to resolve the issue.
EX1254044: Microsoft Confirms the Issue
In the reddit.com thread linked above, as well as on Bleeping Computer, I saw that Microsoft confirmed the issue as of March 17, 2026, in the EX1254044 advisory: Microsoft 365 Alert – Service Degradation – Exchange Online – Some users may be unable to use Microsoft Outlook Classic while the Microsoft Teams Meeting Add-in is enabled- ONGOING.
The notice states that some users may be unable to use Microsoft Outlook Classic while the Microsoft Teams Meetings add-in is enabled. As a workaround, users should disable the Teams add-in. Alternatively, Microsoft suggests running an Office repair to update Outlook Classic to the latest version.
Microsoft has determined that an earlier Outlook build version is the cause of the issue. The developers are working with their contacts to ensure that the latest Outlook version is enabled to minimize the impact, Microsoft writes. Is anyone affected by this bug, and do the workarounds mentioned here in this post—from Microsoft or the reddit.com thread—help?
