Microsoft Windows Error Code 0xC00000A6: How to Fix It

Easy 30-60 minutes Medium Severity Verified June 2026
Error Code
0xC00000A6
Brand
Microsoft Windows
Product Type
operating_system
Severity
Medium
DIY Difficulty
Easy
Estimated Fix Time
30-60 minutes
Error code 0xC00000A6 appears when Windows cannot allow an anonymous login. This often happens after system changes or security updates. Follow these steps to restore normal login.
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Tools You'll Need

How to Fix Error Code 0xC00000A6

  1. Restart Your Computer

  2. Boot into Safe Mode

    Ensure you have access to an administrator account.
  3. Run System File Checker (SFC)

    Do not interrupt the scan.
  4. Check Local Security Policy Settings

    Changing security policies can affect system security. Only disable if necessary.
  5. Perform a System Restore

    System Restore will undo recent system changes but does not affect personal files.
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When to Call a Professional

If the error persists after trying all steps, contact Microsoft Support or a certified technician. This may indicate a deeper system corruption or hardware issue.

Frequently Asked Questions

What does error code 0xC00000A6 mean?
It means Windows has blocked an anonymous login attempt. This can happen due to security policy changes or corrupted system files.
Can I fix error 0xC00000A6 without Safe Mode?
If you can log in normally, you can skip Safe Mode. But if you can't log in, Safe Mode is necessary.
Will System Restore delete my files?
No, System Restore does not affect personal files like documents or photos. It only undoes system changes.
Is this error caused by a virus?
While possible, it's not common. Malware can alter security settings. Run a full antivirus scan if you suspect infection.
Can I disable the anonymous login restriction permanently?
Yes, but doing so may reduce security. Only disable it if necessary, and re-enable it after troubleshooting.