Hello ShabirJan,
To better know about your situation, you may try the following steps for troubleshooting:
- Try to use a different network connection to check if issue exists.
- Try to clear device default browser caches (please be kindly noted that this method will removed all related history records and caches).
- Completely exit all Office 365 related applications on device and only start Teams app to test this issue. Temporarily exit any mobile device manager or antivirus.
Meanwhile, if you’ve tried above methods and issue still exists, may I confirm the following information from you?
- Whether your account is pure Office 365 online? If so, you may try to use the default domain (@contoso.onmicrosoft.com) to see if you can login in Teams.
- Please confirm whether other user in same organization have the same issue.
- Issue happened after you entered username and password? When error message prompts, is there any error code next to it?
- Try to check updates for Teams, if there’s no available updates, could you please share the current full version number of it with us?
Best Regards,
Anna