Office 2021 is crashing on opening with Teams

There is no specific KB in the provided material that addresses Outlook 2021 crashing specifically due to the Microsoft Teams Meeting add-in.

From the available guidance, the recommended approach is to troubleshoot and repair the Teams Meeting add-in rather than permanently disabling it:

1. Verify the Teams Meeting add-in status in Outlook
   • In Outlook 2021, go to File > Options > Add-ins.
   • At the bottom, under Manage, select COM Add-ins and choose Go.
   • Confirm Microsoft Teams Meeting Add-in for Microsoft Office is present.
   • If it is disabled, enable it and select OK.
2. Ensure Outlook and Teams run in the same context
   • Right‑click the Outlook and Teams shortcuts.
   • Select Properties > Compatibility.
   • Make sure Run this program as an administrator is unchecked for both.
   • Running one as admin and the other as standard user can cause add‑in issues and instability.
3. Restart order
   • Fully close Outlook and Teams.
   • Start Microsoft Teams first.
   • Then start Outlook and test whether Outlook still crashes.
4. Reinstall the Teams desktop client
   • Close Outlook and Teams.
   • Uninstall Teams from Settings > Apps on Windows.
   • Reinstall the latest Teams client from the official download page referenced in the documentation.
   • Restart the machine.
   • Start Teams first, then Outlook, and verify if Outlook remains stable with the add‑in enabled.
5. Use the Teams Meeting add‑in troubleshooter for classic Outlook
   • For classic Outlook for Windows (including Outlook 2021), use the classic Teams add‑in for classic Outlook troubleshooter described in the documentation.
   • Run it on Windows 10 or later, on the same PC where Outlook is installed, and follow the steps in the Get Help window to repair or reinstall the add‑in.
6. Advanced: manual registration (if needed)
   • If the add‑in is still problematic after the above steps, the documentation recommends manually registering the add‑in DLL (via PowerShell or Command Prompt) following the steps in the referenced article about the Teams meeting add‑in missing from Outlook and new Teams.
   • This is typically handled by IT admins and may resolve deeper registration issues that cause crashes.
7. General stability checks
   • Ensure Office 2021 and Teams are fully updated.
   • Avoid multiple Office versions on the same machine, as this can interfere with the add‑in.
   • Temporarily disable other Outlook add‑ins to rule out conflicts.

If Outlook 2021 continues to crash with the Teams add‑in enabled after these steps, the documented guidance is to escalate to IT admin or Microsoft Support for deeper investigation (for example, group policy or registry‑level issues). No specific KB hotfix is identified in the provided context as a universal “solid fix” for this scenario.

References:

• Understanding the Microsoft Teams Meeting Add-in for Outlook: Eligibility, Issues, and Troubleshooting
• Troubleshoot the Teams Meeting add-in in Outlook for Windows