Teams Sign-In Loop

A sign-in loop occurs when Teams repeatedly asks for your password, flashes the login screen and returns to the sign-in prompt, or displays a blank white window after entering credentials. This typically happens when cached authentication tokens become corrupted or when there is a conflict between multiple Microsoft accounts on your device.

Step 1: Clear Saved Credentials

Corrupted or outdated credentials stored in your system’s credential manager are the most common cause of authentication loops.

On Windows:

1. Open Credential Manager (search from the Start menu).
2. Click Windows Credentials.
3. Look for entries containing any of these:
   • MicrosoftTeams
   • msteams
   • login.microsoftonline.com
   • Microsoft Office
4. Click each matching entry and select Remove.

# PowerShell: List and remove Teams-related credentials
cmdkey /list | Select-String "teams|microsoft"
# Then remove each one:
cmdkey /delete:LegacyGeneric:target=MicrosoftTeams

On macOS:

1. Open Keychain Access (search via Spotlight).
2. Search for microsoft and teams.
3. Delete all matching items (passwords, certificates, and internet passwords).
4. You may be prompted for your macOS login password to authorize the deletion.

After clearing credentials, restart Teams and sign in with your work or school account.

Step 2: Delete Teams Cache and Auth Data

Beyond credentials, Teams stores authentication tokens locally that can become stale after password changes or account policy updates.

On Windows:

1. Fully quit Teams (right-click system tray icon > Quit, then confirm in Task Manager).
2. Delete the following directories:

rmdir /s /q "%appdata%\Microsoft\Teams"
rmdir /s /q "%localappdata%\Microsoft\Teams"
rmdir /s /q "%localappdata%\Microsoft\IdentityCache"
rmdir /s /q "%localappdata%\Microsoft\OneAuth"

On macOS:

rm -rf ~/Library/Application\ Support/Microsoft/Teams
rm -rf ~/Library/Caches/com.microsoft.teams*
rm -rf ~/Library/Group\ Containers/*.com.microsoft.teams*

3. Restart your computer before relaunching Teams.
4. When Teams opens, enter your email address and password fresh — do not use any saved account suggestions.

Step 3: Check Account and License Status

If your credentials are correct but sign-in still fails, the issue may be with your account or license assignment.

1. Try signing in at https://teams.microsoft.com in a private/incognito browser window.

   • If this works, the problem is local to your desktop client.
   • If this also fails, the issue is account-side.

2. Verify your account status:

   • Go to https://myaccount.microsoft.com and check that you can sign in.
   • If your password recently changed or expired, use the new password.

3. Confirm your Teams license:

   • Ask your IT admin to check the Microsoft 365 Admin Center > Users > your account > Licenses and apps.
   • Ensure a license that includes Teams (e.g., Microsoft 365 Business Basic, E3, E5) is assigned.
   • If the license was recently removed and re-added, it can take up to 24 hours to propagate.

Step 4: Resolve Conditional Access and MFA Issues

Conditional Access policies and multi-factor authentication settings can create sign-in loops when they fail silently.

1. If your organization uses Conditional Access, your device must meet specific compliance requirements:

   • Device enrollment in Microsoft Intune or another MDM solution
   • OS version requirements (e.g., minimum Windows version)
   • Network location restrictions (some policies only allow sign-in from corporate networks)

2. Check your MFA status:

   • Go to https://aka.ms/mfasetup and verify your authentication methods.
   • If your MFA method (phone number, authenticator app) changed, update it before attempting to sign in to Teams.

3. If you are stuck in a loop where MFA prompts but never completes:

   • Clear browser cookies for login.microsoftonline.com.
   • Try a different authentication method (SMS instead of app notification, or vice versa).
   • Contact your IT admin to revoke all active sessions for your account in Azure AD.

# Admin PowerShell: Revoke user sessions (requires admin rights)
Revoke-AzureADUserAllRefreshToken -ObjectId "user@company.com"

Step 5: Reinstall Teams with a Clean Profile

If the sign-in loop persists after clearing all credentials and cache, perform a complete clean installation.

1. Uninstall Teams:

   • Windows: Settings > Apps > find Microsoft Teams > Uninstall.
   • macOS: Drag Teams from Applications to Trash.

2. Remove all remnant data:

:: Windows: Complete cleanup
rmdir /s /q "%appdata%\Microsoft\Teams"
rmdir /s /q "%localappdata%\Microsoft\Teams"
rmdir /s /q "%localappdata%\Packages\MSTeams_8wekyb3d8bbwe"
rmdir /s /q "%localappdata%\Microsoft\IdentityCache"
rmdir /s /q "%localappdata%\Microsoft\OneAuth"

# macOS: Complete cleanup
rm -rf ~/Library/Application\ Support/Microsoft/Teams
rm -rf ~/Library/Application\ Support/Microsoft/OneAuth
rm -rf ~/Library/Preferences/com.microsoft.teams*
rm -rf ~/Library/Caches/com.microsoft.teams*

3. Restart your computer.
4. Download Teams from https://www.microsoft.com/en-us/microsoft-teams/download-app.
5. Install and sign in. If prompted for an account, type your email manually rather than selecting from cached suggestions.

• If you have both a personal Microsoft account and a work/school account, ensure you are signing in with the correct one. Teams may default to the wrong account if both are cached on your device.