Teams Add-In is no longer displayed in Outlook since 1.07.2025 - what can I do?

Hello,
it seems like you are hitting a known issue with the Microsoft Teams Meeting add-in in Outlook 2019 that has been occurring for several users since late June/early July 2025 - specifically with version 1.25.14602. The add-in does not load properly even though it is marked as active, and you may experience errors like "CFastConnect::OnStartupComplete" in the logs. Microsoft has tracked this as Incident TM1104705, which is related to delays or freezes in the Outlook calendar and has now been marked as resolved.

However, the symptoms persist for some users, possibly due to an update of the add-in.
Since you have already tried the usual steps (uninstall/reinstall, repair, registry fixes), here are a few advanced troubleshooting steps based on Microsoft's recommendations:

Check and correct the LoadBehavior value in the registry

• Open the registry editor (regedit.exe) as administrator.
• Navigate to: HKEY_CURRENT_USER\\SOFTWARE\\Microsoft\\Office\\Outlook\\Addins\\TeamsAddin.FastConnect.
• Search for the LoadBehavior entry - it should be set to 3 (for "Load at Startup"). If not, change it to 3.
• Close regedit, restart Outlook.

Re-register the DLL manually

• Close Outlook and Teams completely (check via Task Manager).
• Open a command prompt as administrator.
• Navigate to %LocalAppData%\\Microsoft\\TeamsMeetingAddin and find the subfolder with the highest version number (e.g. 1.25.14602).
• For 64-bit Office: Execute: %SystemRoot%\\System32\\regsvr32.exe /n /i:user <path>\\x64\\Microsoft.Teams.AddinLoader.dll
• For 32-bit Office: %SystemRoot%\\SysWOW64\\regsvr32.exe /n /i:user <pfad>\\x86\\Microsoft.Teams.AddinLoader.dll
• Start Teams, log out and log in again, then Outlook.</path></path>

Rollback to an older add-in version (workaround)

• Close Outlook and Teams.
• Go to %LocalAppData%\\Microsoft\\TeamsMeetingAddin.
• Rename the folder 1.25.14602 (e.g. to 1.25.14602_old) or delete it.
• Copy an older folder (e.g. 1.25.14205, if available) and rename it to 1.25.14602.
• Restart Teams - it should reinstall the add-in. If it is disabled, enable it in Outlook under File > Options > Add-Ins >COM-Add-Ins.
• Note: This could temporarily limit the functionality until Microsoft pushes an update.

I hope that one of these steps will help to solve the problem.

ATTENTION: Microsoft will end all support, including updates and patches as of October 14th. Quelle hier