Fixes / Teams · Checked

Teams error code caa20002: what it means and how to fix it

Short answer

Error caa20002 (0xCAA20002) means Teams tried to sign you in but Microsoft's sign-in service (Microsoft Entra ID) turned down the request. Usually the cause is saved sign-in data that is stale or points at the wrong account. The most likely fix is to quit Teams completely, clear or reset the Teams cache, restart Teams and sign in again with your work or school email.

What this message means

Codes starting with CAA come from the Windows and Microsoft 365 sign-in components that Teams relies on to get an access token. The CAA2xxxx group means the sign-in server answered, but it rejected the request. So your internet connection is working, and the problem is the identity or account details being sent. Typical reasons are a cached token for another account, a personal Microsoft account and a work account that share the same email address, or an organization (tenant) that can't be found or is no longer active. In some cases the server-side message behind it is AADSTS90002, "Tenant not found".

Common causes

CauseHow to tell
Stale or corrupted sign-in data in the Teams cacheTeams worked before, and the error appeared after an update, a password change or a sleep/resume. Signing in at teams.microsoft.com in a browser works fine.
Teams is using the wrong account (personal vs work or school)Your email address is used for both a personal Microsoft account and a work or school account, or the sign-in window offers several accounts. The error appears right after you pick one.
The Windows work or school connection is broken or out of dateOutlook, OneDrive or other Office apps on the same Windows PC also ask you to sign in again or fail silently. Under Settings > Accounts > Access work or school, the account is missing or shows an error.
The organization (tenant) can't be found or the account has no active Teams licenseThe web version at teams.microsoft.com also fails, sometimes showing AADSTS90002 "Tenant not found". This is common with a trial or a school or company subscription that has expired, or after your account was moved or removed.
Wrong system date and timeThe clock in the taskbar or menu bar is off by several minutes or more, or shows the wrong time zone. Other secure websites may also show certificate warnings.

How to fix it

1. Check whether the problem is only in the desktop app

  1. Open a private or incognito browser window.
  2. Go to https://teams.microsoft.com and sign in with the same email address.
  3. If the web version works, the problem is on your computer. Continue with the fixes below.
  4. If the web version also fails, or shows AADSTS90002 or a message saying your account can't be found, skip to the fix about the account or organization.

2. Reset or clear the cache in new Teams

New Teams on Windows 10 and Windows 11

  1. Right-click the Teams icon in the taskbar notification area and select Quit.
  2. Open Settings, then go to Apps > Installed apps and type Microsoft Teams in the search box.
  3. Next to Microsoft Teams, select More options (...) > Advanced options.
  4. In the Reset section, select Reset. This clears app data, including personal Teams settings.
  5. Alternatively, press Windows key + R, enter %userprofile%\appdata\local\Packages\MSTeams_8wekyb3d8bbwe\LocalCache\Microsoft\MSTeams, select OK, and delete everything in that folder.
  6. Start Teams and sign in again.

3. Clear the Teams cache on a Mac

New Teams on macOS

  1. Quit Teams with Command (⌘)-Q.
  2. Open Finder, go to Applications > Utilities, and double-click Terminal.
  3. Run: rm -rf ~/Library/Group\ Containers/UBF8T346G9.com.microsoft.teams
  4. Run: rm -rf ~/Library/Containers/com.microsoft.teams2
  5. Open Teams and sign in again.

4. Reconnect your work or school account in Windows

Windows 10 and Windows 11

  1. Quit Teams from the taskbar notification area.
  2. Open Settings > Accounts > Access work or school.
  3. If your work or school account is listed, select it, choose Disconnect and confirm. Don't do this on a company-managed PC unless IT approves, because it can remove device management.
  4. Select Connect (Add an account on Windows 11), then sign in with your work or school email.
  5. Restart the PC, open Teams, and choose the work or school account when asked.

5. Correct the date and time

  1. Windows 11: go to Settings > Time & language > Date & time, then turn on Set time automatically and Set time zone automatically. Select Sync now.
  2. Windows 10: go to Settings > Time & Language > Date & time and turn on the same two options.
  3. Mac (macOS Ventura and later): go to System Settings > General > Date & Time and turn on Set time and date automatically.
  4. Quit and reopen Teams, then sign in again.

6. Check the account or organization, then reinstall Teams

  1. Sign in at https://portal.office.com with the same email address and check that Teams appears among your apps. If sign-in fails there too, the account or organization is the problem and only your IT admin (or Microsoft support, for a business you own) can fix it.
  2. If your email is used for both a personal and a work account, choose Work or school account when Teams asks which one to use.
  3. If the account is fine, uninstall Teams from Settings > Apps > Installed apps (Windows) or move it to the Trash (Mac).
  4. Windows, classic Teams only: press Windows key + R, open %appdata%\Microsoft and delete the Teams folder.
  5. Download Teams again from microsoft.com/microsoft-teams/download-app, install it, and sign in.

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Still not fixed?

If the web version also fails, the problem is on the account side and not on your computer. Contact your IT or Microsoft 365 administrator and give them the exact code (0xCAA20002), the time it happened and your email address. They can run the Teams Sign-in diagnostic in the Microsoft 365 admin center, or the Teams Sign in test at testconnectivity.microsoft.com, and check the Entra ID sign-in logs for the matching AADSTS error. If you run the Microsoft 365 subscription yourself, open a support request from the admin center and include the Teams debug logs.

Questions people ask

Is caa20002 a problem with my internet connection?

Usually not. Network failures show different codes, such as 0xCAA82EE2 (timeout) or 0xCAA82EE7 (server name couldn't be resolved). caa20002 means Microsoft's sign-in server received your request and rejected it.

Why does Teams work in the browser but not in the desktop app?

The browser uses a fresh sign-in, while the desktop app reuses sign-in data saved on your computer and in Windows. If the web version works, clearing the Teams cache or reconnecting your work account in Windows usually fixes the desktop app.

Will clearing the Teams cache delete my chats or files?

No. Chats, channels and files are stored in Microsoft 365, not in the cache. Resetting the new Teams app only removes local data such as your personal settings, and you have to sign in again.

Can I fix caa20002 myself on a work computer?

Clearing the cache and fixing the clock are safe to try yourself. If the error is caused by your organization's account setup, a missing license or a tenant that can't be found, only your IT administrator can fix it.

What is the difference between caa20002 and caa20003 or caa20004?

All three are sign-in authorization errors. Microsoft links 0xCAA20003 to a wrong date and time and 0xCAA20004 to Conditional Access policies that need admin approval. caa20002 is more general and usually comes down to cached credentials or the wrong account.

Sources

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