How to reinstall Microsoft Teams Add-in for Outlook

Question

How to reinstall Microsoft Teams Add-in for Outlook

Shane Bucher 30

For our end users we are having issues with Microsoft Teams Add-in for Outlook disappearing.
The steps I've taken

Uninstalled Teams and Reinstalled
Registered the new teams as the chat app for Microsoft 365 Apps
Manually ran the UninstallTMA.ps1 scripts, and added the registry keys associated with the teams addin.
Tried Manually installing the TeamsAddin through the MSI in the hidden WindowsApp Folder.
Checked any registry keys that may prevent MSI installations in policies that we do not have.

The error we are getting with the MSI is User's image

Let me know if I missed anything.

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3 answers

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Answer 1

Shane Bucher 30

Installed Teams from the web then installed Teams VDI over it. Opened teams and then outlook then the teams meeting add-in was there.

Anonymous

2025-08-22T17:09:53.5466667+00:00

Have a great day, @Shane Bucher!

It was truly a pleasure for us to work with you on this matter. It’s great to hear that you’ve successfully resolved the issue by installing Teams from the web and subsequently applying the Teams VDI installation. As confirmed, the Teams Meeting add-in is now visible upon launching both Teams and Outlook.

By upvoting, you are helping to highlight this information for other community members with similar queries, enabling them to find solutions more quickly.

Once again, we really appreciate your time and your cooperation in fixing the problem. We value you as our customer and thank you for contacting the Microsoft Q&A forum. If you need any other assistance, please don’t hesitate to reach out again and I would be happy to help you.

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Answer 2

Anonymous

Have a great day, @Shane Bucher! I hope you're doing well.

I'm contacted to follow up on the issue you reported earlier about issues with Microsoft Teams. It's been a while since we've heard from you, and I'd like to check if the issue has been resolved or if you're still having difficulties.

Please let us know as soon as possible so that we can provide further assistance if needed. Thank you for your time and cooperation.

If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment”.

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Shane Bucher 30 Reputation points

2025-08-12T19:55:58.4866667+00:00

This did not work, just tried it today, still getting the same error on the MSI.

Answer 3

Dear @Shane Bucher,

Thank you for contacting us regarding the issue with the Microsoft Teams Meeting Add-in for Outlook. We understand how critical this functionality is to your daily operations and appreciate the detailed steps you've already taken to resolve the problem.

From your report, we see that you have try several steps such as uninstalled and reinstalled Microsoft Teams, set the new Teams client as the default chat app for Microsoft 365, executed the UninstallTMA.ps1 script and manually added the relevant registry keys. However, the problem still persists. Here are some steps you can take to troubleshoot and potentially resolve the issue:

Uninstall Existing Add-in Components:

Via Settings: Go to Windows Settings > Apps > Installed Apps and uninstall Teams Meeting Add-in for Microsoft Office if found.
Via PowerShell (Optional):
- Use UninstallOldTMA.ps1 for versions starting with 1.23.
- Use UninstallTMA.ps1 for other versions.
- These scripts clean up registry entries and leftover files. Run them in an elevated PowerShell prompt if needed.

Close Outlook and Teams:

Fully exit Outlook (check Task Manager for lingering processes).
Quit Teams from the system tray to prevent interference during reinstall.

Reinstall via New Teams Client:

Launch New Teams and log in.
Wait a few minutes for automatic add-in registration.
Verify Installation: Check Settings > Apps > Installed Apps for the add-in entry.
Ensure you have the latest Teams version.
Reinstall Teams from Microsoft’s official site.

Launch Outlook and Verify the Add-in:

Check Calendar Ribbon: Open Outlook and create a new meeting. Look for the “Teams Meeting” button on the ribbon.
Check COM Add-ins:
Go to File > Options > Add-Ins.
At the bottom, set Manage to “COM Add-ins” and click Go.
- Look for Microsoft Teams Meeting Add-in for Microsoft Office.
  - If unchecked, tick the box, click OK, and restart Outlook.
  - If missing, the add-in isn’t installed or registered—proceed to manual fixes.
  - Avoid Admin Mode: Ensure Outlook is not running as Administrator, which can block add-ins from loading.

Additional Manual Fixes (if Add-in Still Missing):

Re-register the Add-in DLL

Locate the DLL file:
- Path: %LocalAppData%\Microsoft\TeamsMeetingAddin<version>\x64\ (for 64-bit Office) or x86\ (for 32-bit).
Open Command Prompt as Administrator and run:
- For 64-bit:
%SystemRoot%\System32\regsvr32.exe /n /i:user "<path>\Microsoft.Teams.AddinLoader.dll"
For 32-bit:
%SystemRoot%\SysWOW64\regsvr32.exe /n /i:user "<path>\Microsoft.Teams.AddinLoader.dll"
Restart Teams and Outlook.

I hope you find this message is helpful. If you have any further questions, please don’t hesitate to reach out if you have further questions or need assistance implementing any of the suggested workarounds. Thank you for your kindness and understanding.

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Shane Bucher 30 Reputation points

2025-08-05T17:51:56.3+00:00

When we run the Regsevr to restart the .dll it does not work because it does not having the supporting files, it doesn't have a x86 and x64 folder just the dll and one other file in the folder when we reinstall teams.
Anonymous

2025-08-05T19:56:30.0833333+00:00

Dear @Shane Bucher,

Thanks for your feedback. The Teams Meeting Add-in is a VSTO-based (not COM-based) add-in, so it doesn't rely on regsvr32 or traditional .dll registration. That's why it's failing.

Instead of using regsvr32, the supported method is:

Option 1: Reinstall via the Built-in Teams MSI Installer

Uninstall Teams completely using Microsoft’s Teams Cleanup Tool/script.

Restart the machine.

Reinstall Microsoft Teams from the official installer:
https://www.microsoft.com/en-us/microsoft-teams/download-app

Option 2: Manually Install Add-in (if MSI fails)

If needed, you can manually install the MSI version of the add-in from the hidden folder:

C:\Users<username>\AppData\Local\Microsoft\TeamsMeetingAddin\Installer

Run bash:

TeamsMeetingAddinInstaller.msi

Or install via command line in Powershell:

msiexec /i "TeamsMeetingAddinInstaller.msi" /L*v TeamsAddinInstall.log

Clean Registry Entry

If you need to reset things:

Open regedit

Navigate to: HKEY_CURRENT_USER\Software\Microsoft\Office\Outlook\Addins\TeamsAddin.FastConnect

Delete the key or set LoadBehavior = 3 (if not already)

If you have further questions or need assistance implementing any of the suggested solutions. Thank you for your patience and understanding.

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How to reinstall Microsoft Teams Add-in for Outlook

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