CAA20002 Error Code Microsoft Apps: Fixes

The CAA20002 error code appears in Microsoft apps like Teams, Outlook, and Office when a sign-in or license check fails, usually due to network, proxy, or credential issues. This article explains what triggers it and walks you through the fixes that resolve it in most cases.

What Is the CAA20002 Error Code?

CAA20002 is an authentication-related error that Microsoft 365 applications show when they cannot verify your account or fetch a required token. It is most commonly reported in Microsoft Teams, but it also occurs in Outlook, Word, Excel, and other Office apps. The error message typically reads “We’re unable to complete your request” or “Something went wrong” with the code CAA20002.

The root cause is almost always one of the following:

• A proxy or firewall blocking Microsoft’s authentication endpoints
• Corrupted cached credentials stored in Windows Credential Manager
• An outdated or misconfigured system time (the token validation fails if your clock is off)
• A broken Office or Teams installation after an update
• Network issues such as a VPN that interferes with the connection

Because the code is generic, you need to work through the fixes below in order, testing after each one.

Before You Start: Check System Time and Network

Many CAA20002 errors are caused by a mismatched system clock. Microsoft’s servers issue time-limited tokens, and if your device’s time is more than a few minutes off, the token is rejected.

1. Right-click the clock in the taskbar and select Adjust date/time.
2. Turn on Set time automatically and Set time zone automatically.
3. If they are already on, toggle them off and on again, then restart the app.

Next, verify that you can reach Microsoft’s authentication servers. Open a browser and go to login.microsoftonline.com. If the page loads, your network can reach the endpoint. If it does not, your proxy or firewall is blocking it. In that case, contact your IT administrator or temporarily disable your VPN and try again.

Fix 1: Clear Cached Credentials in Windows Credential Manager

Windows stores sign-in tokens in Credential Manager. If those tokens become stale or corrupted, Microsoft apps fail with CAA20002.

1. Open Control Panel > User Accounts > Credential Manager.
2. Click Windows Credentials.
3. Look for any entry that contains MicrosoftOffice, MicrosoftTeams, or Microsoft AAD.
4. Click the arrow next to each entry and select Remove.
5. Close Credential Manager and restart the affected app. You will be asked to sign in again.

If you are not comfortable deleting credentials manually, you can use the Credential Manager command-line tool as an administrator: cmdkey /list shows all stored credentials, and cmdkey /delete:<target> removes a specific one. Only delete entries related to Microsoft apps.

Fix 2: Reset Microsoft Teams or Office via the App Settings

Teams has a built-in reset that clears cached files without uninstalling. For Teams (classic), close the app completely, then press Win + R, type %appdata%\Microsoft\Teams, and delete the contents of the Cache, Code Cache, GPUCache, and Local Storage folders. Relaunch Teams and sign in again.

For Microsoft 365 apps (Word, Excel, Outlook), use the Quick Repair tool:

1. Open Settings > Apps > Installed apps.
2. Find Microsoft 365 (or Office), click the three-dot menu, and select Advanced options.
3. Click Repair (Quick Repair). If that does not help, run Online Repair after.

For Outlook specifically, you can also try creating a new Outlook profile, because a corrupted profile can trigger authentication errors.

Fix 3: Re-register the App with Windows (For UWP/Store Apps)

If you installed Microsoft Teams (work or school) from the Microsoft Store, the app registration can become broken. Re-register it using PowerShell:

1. Right-click the Start button and select Windows PowerShell (Admin) or Terminal (Admin).
2. Run this command: Get-AppxPackage -Name "Microsoft.Teams" | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register "$($_.InstallLocation)\AppXManifest.xml"}
3. Wait for the command to finish, then restart the app.

If you are using the new Teams (which is a regular desktop app), this step does not apply. For other Microsoft Store apps that show CAA20002, you can also try Settings > Apps > Installed apps, find the app, and click Reset. This clears the app’s data and may fix the authentication state.

Fix 4: Check Proxy and Firewall Settings

Corporate networks often use proxies that strip or modify authentication headers. If you are on a work or school network, ask your IT team to allowlist the following Microsoft endpoints (they are official, but the list changes, so get the latest from Microsoft’s documentation):

• login.microsoftonline.com
• login.live.com
• graph.microsoft.com
• *.teams.microsoft.com (for Teams)
• outlook.office.com (for Outlook)

If you are on a home network, temporarily disable your antivirus firewall or VPN to see if that resolves the error. If it does, reconfigure the firewall to allow the Microsoft apps through. For VPN users, try connecting without the VPN, or switch to a different VPN server.

Fix 5: Clear the DNS Cache and Renew IP

A corrupted DNS cache can prevent the app from resolving Microsoft’s servers correctly. Run these commands in an elevated Command Prompt:

1. Press Win + R, type cmd, then press Ctrl+Shift+Enter to run as administrator.
2. Type ipconfig /flushdns and press Enter.
3. Type ipconfig /release and press Enter.
4. Type ipconfig /renew and press Enter.
5. Restart your computer.

This often fixes intermittent network issues that cause CAA20002. If the error persists, you can also try switching your DNS server to a public one like Google (8.8.8.8) or Cloudflare (1.1.1.1) temporarily to see if that helps.

Frequently Asked Questions

Does CAA20002 mean my account is locked?

No. CAA20002 is not a lockout error. It means the app couldn’t complete the sign-in process due to a technical issue. If your account were locked, you would see a different message about contacting your administrator.

Will uninstalling and reinstalling Teams fix CAA20002?

Sometimes, but only if the installation is corrupted. Before reinstalling, try the credential clearing and repair steps, because they are faster and often work. If you do reinstall, use the official installer from Microsoft and sign out of all other Office apps first.

Why does CAA20002 appear only on my work computer?

That usually points to a proxy or group policy issue. Your IT department may have set a proxy that blocks certain Microsoft endpoints, or a security policy is interfering with the authentication flow. Contact your IT support with the error code and the steps you’ve already tried.

Can CAA20002 affect Microsoft Teams on a Mac?

Yes, the error can appear on macOS as well. The fixes are similar: clear the Teams cache (in ~/Library/Application Support/Microsoft/Teams), check your system time, and ensure your network can reach Microsoft’s servers. The Credential Manager steps are Windows-specific, but on Mac you can delete the keychain entries for Microsoft Teams via the Keychain Access app.

Is there a way to prevent CAA20002 from happening again?

Keep your Windows and Office apps updated, avoid using VPNs that route through unusual locations, and periodically clear cached credentials if you switch accounts often. Also, make sure your system time is set to automatic, as a drifting clock is a common trigger.

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