Microsoft Windows Error Code 0xC000021F: How to Fix It

Medium 30-60 minutes Medium Severity Verified June 2026
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Error Code
0xC000021F
Brand
Microsoft Windows
Product Type
operating_system
Severity
Medium
DIY Difficulty
Medium
Estimated Fix Time
30-60 minutes
Error code 0xC000021F indicates a RPC reply mismatch in Windows, often caused by corrupted system files, faulty drivers, or problematic updates. This stop error can prevent your PC from booting, but it's fixable with a few targeted steps. Follow this guide to resolve the issue and get your system running again.
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Tools You'll Need

How to Fix Error Code 0xC000021F

  1. Boot into Safe Mode

  2. Run System File Checker (SFC)

    Do not close the Command Prompt window during the scan.

  3. Run DISM Tool

    Ensure you have a stable internet connection as DISM may download files from Windows Update.

  4. Uninstall Recent Updates

  5. Update or Roll Back Drivers

  6. Perform a System Restore

    System Restore requires a restore point to be available. If none exist, skip this step.

  7. Check Disk for Errors

    Back up important data before running chkdsk as it may fix issues that could cause data loss.

  8. Perform a Startup Repair

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When to Call a Professional

If none of the above steps resolve the error, or if you suspect hardware failure (e.g., failing hard drive or RAM), contact a professional technician. Data recovery services may also be needed if you cannot access your files.

Frequently Asked Questions

What causes Windows error 0xC000021F?
This error is typically caused by corrupted system files, problematic Windows updates, faulty drivers, or malware. It can also occur due to issues with the RPC subsystem.
Can I fix error 0xC000021F without losing data?
Yes, most fixes like Safe Mode, SFC, DISM, and System Restore do not affect personal files. However, always back up important data before attempting repairs.
Is error 0xC000021F a hardware issue?
It's primarily a software issue, but faulty hardware like a failing hard drive or bad RAM can cause similar symptoms. Run hardware diagnostics if software fixes fail.
How do I boot into Safe Mode if I can't access Windows?
Use Windows installation media to boot, then select 'Repair your computer' > 'Troubleshoot' > 'Advanced options' > 'Command Prompt'. Type 'bcdedit /set {default} safeboot minimal' and restart. Alternatively, interrupt the boot process three times to trigger Automatic Repair, then go to Advanced options > Startup Settings > Restart > press 4 or 5.
Will reinstalling Windows fix error 0xC000021F?
Yes, a clean installation will resolve the error, but it will erase all data on the system drive. Try other fixes first, or use the 'Reset this PC' option to keep your files.

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