1 Uninstall Teams using the Programs & Features Control Panel
2 Restart Computer
3 a Type Credential Manager in Windows search box and open it.
b Open Windows Credentials tab remove all the credentials named msteams_adalsso/adal_context
4 Go to %appdata% and remove Microsoft Teams.
5 Go to %appdata% enter Microsoft and remove Teams folder.
6 Restart Computer
7 Reinstall Teams
8 Restart again.
9 Wait for Teams to start up on its own. It will ask you to Authenticate. Enter Authentication details.
10 Confirm that users Teams are available and that the files for each Team are accessible.