Microsoft Teams - Troubleshoot Teams client startup

Last week I had some problems with Microsoft Teams and especially with the desktop client. It got stuck in a loop and wouldn't start at all. Because of these problems with the desktop client, I started looking at how to troubleshoot such problems. After reading through some articles and doing some testing myself, I wanted to share with you the approach you can take if the desktop client doesn't boot. If your users report a problem when they start the Teams desktop client, determine if the issue is related to the desktop client or the Teams service.

Instruct the user to open Microsoft Edge (or another browser) and use the Teams web app?to sign in. If the user can successfully use Teams in the browser, you can assume the problem is related to the desktop client. If the user also experiences problems connecting with a browser, then check service health in the Microsoft 365 admin center.

To troubleshoot the Teams desktop client you can use the following high-level procedure:

1. First examine the?SquirrelSetup.log?file located in the?%LocalAppData%\Microsoft\Teams?folder. Go to the end of the file and verify if any errors are displayed.

1. Delete the Teams client cache:

• Close Teams, and if necessary, use Task Manager to ensure all Teams processes are ended.
• In File Explorer, navigate to?%appdata%\Microsoft\Teams.
• Open the?Cache?folder and delete its contents.
• Restart Teams and try to sign in.
• If that doesn’t resolve the issue, in?%appdata%\Microsoft\Teams, consider deleting the contents of the following subfolders:

\application cache\cache

\blob_storage

\databases

\GPUcache

\IndexedDB

\Local Storage

\tmp

3. Restart Teams and try to sign in.

4. If clearing the cache doesn’t help, consider installing the latest updates.

5. Finally, consider reinstalling the Teams desktop client. In my case deleting the content of all the subfolders helped fixing the problem.