Microsoft Teams Keeps Asking to Sign In (Login Loop)

How to fix it

Try these in order — the most common fix is first.

1. 1. Check whether the account itself works

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   1. Open a private browser window and sign in at teams.microsoft.com
   2. If the web works, the problem is the desktop app or device
   3. If the web also fails, contact your admin: the account, license or policy is the issue
   Did this fix it? Yes No

2. 2. Clear the Teams cache

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   1. Quit Teams
   2. Windows: Settings > Apps > Installed apps > Microsoft Teams > Advanced options > Reset
   3. Mac: in Terminal run rm -rf ~/Library/Group\ Containers/UBF8T346G9.com.microsoft.teams and rm -rf ~/Library/Containers/com.microsoft.teams2
   4. Open Teams and sign in once (don't click Sign in repeatedly)
   Did this fix it? Yes No

3. 3. Remove stale work accounts from Windows

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   1. Open Settings > Accounts > Access work or school
   2. Disconnect old or duplicate work accounts (not your current managed device account if IT manages it)
   3. Restart and sign in to Teams again
   Did this fix it? Yes No

4. 4. Turn off VPN/proxy and check TLS

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   1. Disconnect VPN and retry sign-in
   2. In Windows Internet Options > Advanced, make sure TLS 1.2 is enabled
   3. Temporarily allow Teams through third-party firewall/antivirus
   Did this fix it? Yes No

5. 5. Ask IT to check license and device

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   1. Give your admin the exact error code from the sign-in window
   2. Admin checks that a Teams license is assigned in the Microsoft 365 admin center
   3. Admin checks the device is enabled and registered in Microsoft Entra ID
   4. Admin can collect Teams debug logs and open a support case
   Did this fix it? Yes No

Symptoms

Teams prompts for your password again and again, shows 'We couldn't sign you in' with a code such as CAA50021, caa70004 or 0xCAA20003, or signs in on the web but not in the desktop app.

Why it happens

• Corrupted cached credentials or Teams cache
• Device disabled or registration expired in Microsoft Entra ID (CAA50021)
• No Teams license assigned (common after unbundling), causing generic sign-in errors
• VPN, proxy, firewall or disabled TLS blocking authentication (caa70004)
• MFA or conditional access policy blocking the device
• Repeatedly clicking Sign in, which makes retry errors worse

This guide also covers

• teams keeps asking to sign in
• teams login loop
• teams error caa50021
• teams error caa70004
• we couldn't sign you in teams

Other Microsoft Teams errors

• How to Cancel Microsoft Teams Subscription
• Microsoft Teams Not Loading or Stuck on White Screen
• Microsoft Teams Using Too Much Memory
• Microsoft Teams Notifications Not Working
• Microsoft Teams Camera Not Working
• Microsoft Teams Microphone Not Working
• Microsoft Teams Status Stuck on Away or Offline
• Teams Screen Sharing Shows a Black Screen