Teams sign-in problems are frequently caused by a corrupted local cache rather than the account itself, since Teams stores a large amount of local application state.
Common Symptoms
- Teams shows a sign-in loop, returning to the login screen repeatedly
- “We couldn’t sign you in — please try again” with no other detail
- Teams opens but shows a blank or white screen
Possible Causes
- Corrupted local Teams cache
- Conflicting Teams classic vs new Teams installation
- The same conditional access/account issues covered in the Microsoft 365 login guide
Before You Begin
Confirm Teams on the web (teams.microsoft.com) works with the same account — if it does, the problem is local to the desktop app, not the account.
Method 1 — Clear the Teams cache
Fully close Teams
Quit Teams completely, including checking Task Manager for any remaining Teams process.
Delete the cache folder
Navigate to %appdata%MicrosoftTeams (classic) or the new Teams cache location and delete its contents, then relaunch Teams.
Method 2 — Sign out fully and back in
Sign out from account settings
Click your profile picture → Sign out, rather than just closing the window.
Restart and sign in again
Fully quit Teams, reopen it, and sign in from a clean state.
Method 3 — Reinstall Teams
Uninstall via Settings
Settings → Apps → Installed apps → find Microsoft Teams → Uninstall.
Reinstall the latest version
Download and install the current Teams client from Microsoft’s official download page.
If sign-in fails in Teams but works fine in Outlook and OneDrive, the issue is almost certainly local to the Teams app cache, not your account.
Frequently Asked Questions
Does clearing the Teams cache delete my chat history?
No — chat and channel messages are stored in the cloud, not locally. Clearing the cache only removes locally stored app state and temporary files.
Conclusion
Clearing the local cache resolves the majority of Teams sign-in loops — a reinstall is rarely necessary but is a safe fallback if the cache clear doesn’t help.
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