Microsoft Teams Meeting Add-in Causes Outlook Classic to Break
Microsoft Investigates Issue Causing Classic Outlook to Malfunction with Teams Meeting Add-in Enabled
Microsoft is currently addressing a known issue that renders the classic Outlook client unusable for users who have enabled the Microsoft Teams Meeting Add-in. According to an admin center update, some users may experience difficulties using the classic Outlook client while the add-in is enabled.
Temporary Fix
The issue is reportedly caused by a previous Outlook build version, although the exact root cause has not been disclosed. To temporarily resolve the issue, affected users are advised to update their Outlook installation or perform an Online Repair for click-to-run installs, which will reinstall all Office applications.
Resolution Efforts
Microsoft has acknowledged the problem and is working to ensure that the latest Outlook version is enabled to mitigate the impact. The company has identified that the previous Outlook build version is causing the issue and is collaborating with representatives to resolve the problem.
Other Issues
In addition to this issue, Microsoft is also investigating several other problems that cause connection issues in the classic Outlook desktop client, resulting in 0x800CCC0F and 0x80070057 errors during synchronization with Gmail and Yahoo accounts. These issues are not related to the Teams Meeting Add-in problem.
Recent Incidents
In a separate incident, Microsoft recently mitigated a widespread Exchange Online outage that caused disruptions to users. The company has also addressed other classic Outlook issues in the past, including a bug caused by the December 2025 updates that prevented users from accessing encrypted emails.
Recommendations
Users who are experiencing difficulties with the classic Outlook client while using the Teams Meeting Add-in are advised to follow the recommended temporary fixes until a permanent solution is implemented. Microsoft is expected to provide further updates on the issue as more information becomes available.
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