OneDrive Error Codes

How to Fix OneDrive Sign-in Error CAA50021 on PC

Kushani Nimanthika Oct 12, 2026 869 views

Question details

Users are experiencing error 0xCAA50021 when attempting to sign in to the OneDrive sync client or Microsoft 365 apps on their personal computers.

How to Fix OneDrive Error CAA50021 on a Personal Computer

Product: Microsoft OneDrive
Device & OS: Windows
Scenario: Signing in to the OneDrive sync client or authenticating Microsoft 365 applications for work or school.
Observed behavior: The sign-in process fails and displays error code 0xCAA50021, often accompanied by issues related to device registration or Microsoft Entra ID authentication.

Before you start

Verify your internet connection and check if you can successfully sign in to the OneDrive for Business website via a web browser before attempting advanced desktop troubleshooting.

Solution 1Recommended

Reset the OneDrive Sync Client

Resetting OneDrive can resolve various sync and sign-in glitches by clearing the app's cache and configurations without losing your data.

This process will restart the OneDrive app and re-sync your files. It is the most common fix for authentication loops and sync errors.

Open the Run dialog

Press the Windows key + R simultaneously on your keyboard to open the Run dialog box.

Execute the reset command

Type %localappdata%\Microsoft\OneDrive\onedrive.exe /reset into the text box and press Enter or click OK.

Restart OneDrive manually

Wait for the OneDrive cloud icon to disappear and reappear in the system tray. If it does not reappear after a few minutes, open the Start menu, search for OneDrive, and launch it manually.

Sign in again

Enter your Microsoft credentials to sign in and check if the CAA50021 error is resolved.

No Data Loss: Resetting OneDrive only resets the application settings. It does not delete any of your personal or work files.

Solution 2

Re-register Your Device in Windows

Error CAA50021 often occurs when the device's registration status with Microsoft Entra ID (formerly Azure AD) is corrupted or expired.

Solution 3

Check Security Software Interference

Third-party antivirus or firewall software might inadvertently block the authentication traffic required for Microsoft 365 sign-in.

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Frequently Asked Questions

What does OneDrive error 0xCAA50021 mean?

Error 0xCAA50021 is a Microsoft 365 authentication error that typically indicates a problem with device registration in Microsoft Entra ID (Azure AD). It prevents the OneDrive sync client or Office apps from properly verifying your login credentials.

Can I still access my OneDrive files while experiencing this error?

Yes, this error usually only affects the desktop sync client. You can still view, download, and upload your files by logging into the OneDrive for Business website directly through your web browser.

Does resetting OneDrive delete my local files?

No. Resetting the OneDrive client only clears the application's configuration settings and restarts the sync connections. It does not delete any of your personal or work files stored locally or in the cloud.

Why does error CAA50021 only affect one account on my PC?

Device registration issues are often tied to specific work or school accounts. If the token for that specific organization's domain expires or becomes corrupted, only that account will throw the CAA50021 error, while personal Microsoft accounts may continue to work fine.

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