Microsoft Windows Error Code 0xC0000091: How to Fix It
Easy 30 minutes to 2 hours (depending on scan times) Medium Severity
Verified June 2026
- Error Code
- 0xC0000091
- Brand
- Microsoft Windows
- Product Type
- operating_system
- Severity
- Medium
- DIY Difficulty
- Easy
- Estimated Fix Time
- 30 minutes to 2 hours (depending on scan times)
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Tools You'll Need
- Administrator access to Windows
How to Fix Error Code 0xC0000091
-
Restart Your Computer
-
Update Windows and Drivers
-
Run System File Checker (SFC)
-
Check for Disk Errors
This process can take a long time. Do not interrupt it. -
Test Your RAM
Back up important data before running memory tests as a precaution. -
Repair or Reinstall Problematic Software
-
Perform a System Restore
System Restore does not affect personal files but will remove recently installed apps and drivers.
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When to Call a Professional
If the error persists after all steps, consider professional help. Persistent float overflow may indicate failing hardware (CPU or RAM) or a deeply corrupted system that requires a clean Windows installation.Frequently Asked Questions
What causes Windows error 0xC0000091?
This error is caused by a floating-point overflow, often due to outdated drivers, corrupted system files, or faulty hardware like RAM or CPU.
Can I fix error 0xC0000091 without reinstalling Windows?
Yes, often you can fix it by updating drivers, running SFC, checking disk errors, or using System Restore. Reinstalling is a last resort.
Is error 0xC0000091 a sign of hardware failure?
It can be. If software fixes don't work, test your RAM and check for overheating CPU. If problems persist, hardware replacement may be needed.
Does error 0xC0000091 damage my computer?
The error itself doesn't damage hardware, but it may cause application crashes or data loss. Promptly fixing it is recommended.
How do I prevent error 0xC0000091 in the future?
Keep Windows and drivers updated, run regular disk checks, and avoid overclocking. Regularly back up important data.