0xCAA20003 Severity: High There was a problem with authorization
Teams cannot authenticate. Usually caused by conflicting accounts, wrong system time, or a corrupted token cache.
Affected systems
Symptoms
- Teams login fails with code 0xCAA20003
- Endless sign-in loop in the desktop client
- Error message 'There was a problem with authorization'
- Same account works on a different device
Possible causes
- Multiple Microsoft accounts on the same Windows profile
- Wrong system time or timezone (auth tokens are time-bound)
- Corrupted token cache after update or crash
- Conditional Access policy blocking the device
- Multiple tenants causing browser SSO conflict
Solutions
1.Check and auto-set system time
Windows
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Open Settings, Time and Language, Date and Time.
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Enable 'Set time automatically' and 'Set time zone automatically'.
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Click 'Sync now' and restart Teams.
macOS
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Open System Settings, General, Date and Time.
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Enable 'Set date and time automatically'.
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Set time zone to 'Automatic' as well.
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Quit Teams completely and relaunch.
2.Clear the Teams token cache fully
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Quit Teams via Task Manager or Activity Monitor so no process remains.
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Delete the cache folder (classic client).
%appdata%\Microsoft\Teams~/Library/Application Support/Microsoft/Teams -
Delete the cache folder (new client).
%localappdata%\Packages\MSTeams_8wekyb3d8bbwe\LocalCache~/Library/Group Containers/UBF8T346G9.com.microsoft.teams -
Restart Teams and sign in fresh.
3.Reconnect your work or school account
Windows
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Open Settings, Accounts, 'Access work or school'.
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Disconnect the affected account.
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Reboot.
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Add the account again, complete MFA, open Teams.
macOS
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Open Keychain Access.
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Search for entries containing 'Microsoft' or 'Office' and delete them.
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Quit Teams, relaunch, sign in.
4.Cross-check in a browser
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Open https://teams.microsoft.com in a private browser window.
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If sign-in works there, it is a local cache problem. If it also fails there, it is the account or tenant policy.
Useful Microsoft endpoints
- Microsoft 365 Service Health shows whether an active Microsoft incident is affecting authentication.
- mysignins.microsoft.com lists your recent sign-ins and active sessions. Sign out suspicious devices, then retry locally.
- myaccount.microsoft.com for the overview of your account.
- Microsoft Learn - Teams Sign-in Errors is the official catalog.
When you work in multiple organizations
If you are a guest or contractor in multiple tenants, browser SSO can get confused. Rule of thumb: whenever 0xCAA20003 appears and your account works in the web, the cache is to blame - not your configuration. A clean cache reset fixes more than 80 percent of cases.
When IT must help
If none of the three solutions works, check whether your company has a Conditional Access policy blocking non-compliant devices. The correlation ID from the error page is the fastest way for IT to diagnose.