Authentication Error in teams

Hi Hardik Dave eTurns

Thanks for posting. I understand you’re seeing a recurring “Authentication error” in the Microsoft Teams desktop app each morning, while Teams works normally in the web browser at teams.live.com.

Have you already tried the Q&A Assist suggestions under your thread? In addition, please try the following:

1, Sign out completely, then reset the app

1. Open Teams > profile picture > “Sign out”.
2. Close Teams completely (ensure it’s not running in the system tray).
3. Press Win + R, type ms-settings:appsfeatures, open Installed apps, select “Microsoft Teams (Free)” > Advanced options > click “Reset”.
4. Restart Windows and sign in again.

2, Check WebView2 Runtime

Teams relies on Microsoft Edge WebView2.

• Ensure Microsoft Edge WebView2 Runtime is installed and up to date.
• If missing or corrupted, reinstall it from Microsoft: https://developer.microsoft.com/microsoft-edge/webview2/

3, Verify Windows network state at startup

Since the issue happens in the morning only, please check:

• After boot, confirm Windows shows active internet connectivity before launching Teams.
• Try waiting 1–2 minutes after sign‑in, then start Teams.

This helps rule out a brief network initialization delay that affects the desktop app but not the browser.

As you already confirmed, using Teams on the web (teams.live.com) is a supported workaround while the desktop app issue is being resolved.

Please feel free to let me know how it goes so I can guide you further. Thank you for your time and understanding.

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The behavior indicates a client-side sign-in/authentication problem specific to the desktop app, not to the Teams service itself (since the web URL works). Use these steps that are supported in the context:

1. Verify date and time on the device
   • Incorrect system date/time can cause Teams authentication to fail and show connectivity-type errors.
   • Ensure the PC clock, date, time zone, and automatic time sync are correct, then restart Teams.
   • This directly addresses status code 0xCAA20003 scenarios where authorization fails because secure (HTTPS) connections cannot be established correctly.
2. Check for network/proxy/firewall interference
   • Because the desktop client reports “There is no internet connection” after clearing the Teams cache, verify that:
     • The device is actually online when starting Teams.
     • No proxy, network sniffing tool (for example, Fiddler), or security software is blocking or intercepting Teams traffic.
   • If a proxy or network inspection tool is used, it must be configured correctly to handle HTTPS traffic, otherwise Teams can’t reach the service and will show sign-in/connection errors such as 0xCAA70004/0xCAA70007/0xCAA82EE2/0xCAA82EE7.
   • If this is managed by an organization, involve the IT admin to review firewall and proxy rules for Teams.
3. Reinstall the Teams desktop app cleanly Since deleting only the %appdata%\Microsoft\Teams folder did not help, follow the full manual remediation path:
   1. Uninstall Teams from Windows (Apps & Features / Installed apps).
   2. After uninstalling, go to %appdata%\Microsoft and delete the Teams folder again if it still exists.
   3. Download the latest Teams client and reinstall it. If possible, run the installer as an administrator (right-click → Run as administrator).
   • This sequence is the recommended approach when sign-in problems persist in the desktop client.
4. If the issue persists every morning
   • If the desktop app continues to fail only at certain times (for example, mornings) but the web client always works, this often indicates:
     • Time-based network or proxy policies, or
     • Conditional access / authentication policies in Microsoft Entra ID that intermittently block the rich client.
   • In that case, contact the organization’s IT admin with:
     • Exact error messages and any status codes shown on the Teams sign-in screen.
     • Approximate times when the issue occurs.
   • If needed, the admin can collect Teams debug logs and open a support request as recommended.

During periods when the desktop app fails, continuing to use the Teams web client is a valid workaround until the desktop sign-in issue is fully resolved.

References:

• Why am I having trouble signing in to Microsoft Teams?
• Resolve sign-in errors in Teams