The error code 0x00000021 is associated with a Blue Screen of Death (BSOD) in Windows systems. It translates to “QUOTA_UNDERFLOW,” indicating a problem with how the system manages quotas for resources like memory or network connections.

Here’s a breakdown of the issue, causes, and solutions for the 0x00000021 error:

What is a Quota Underflow?

In Windows, quotas are used to limit the amount of resources a process or user can consume. A quota underflow signifies that the system attempted to return more quota than was previously charged to a specific block. This inconsistency can lead to system instability and crashes.

Causes of the 0x00000021 Error:

• Faulty or Outdated Device Drivers: Buggy, incompatible, or outdated device drivers can cause issues with quota management, leading to underflow errors.
• Software Bugs: Bugs in recently installed software might interfere with system resource management and cause problems with quotas.
• Hardware Problems (Less Likely): In rare cases, malfunctioning hardware components, especially RAM (Random Access Memory), can contribute to system instability and quota errors.

Troubleshooting Steps:

Here are some steps you can try to fix the 0x00000021 error:

Basic Troubleshooting:

1. Restart your computer: A simple restart can sometimes clear temporary glitches that might be causing the problem and resolve driver issues.
2. Update Windows and Drivers: Make sure your Windows system and all device drivers are up-to-date. Outdated software can lead to conflicts and compatibility issues.

Advanced Troubleshooting (proceed with caution):

1. Identify Conflicting Software: If the error started after installing a specific program, consider uninstalling it. The program might be causing conflicts with system resource management, including quotas.
2. Driver Updates (Targeted): If you suspect a particular device driver might be causing the issue, try updating that specific driver. You can update drivers manually through Device Manager or use a driver updater tool (use caution with third-party tools; ensure they are from reputable sources).
3. System File Checker (SFC) and Deployment Image Servicing and Management (DISM) (if comfortable): These tools can scan and repair corrupted system files that might be contributing to the error. Instructions on running these tools can be found on the Microsoft website: https://support.microsoft.com/en-au/topic/use-the-system-file-checker-tool-to-repair-missing-or-corrupted-system-files-79aa86cb-ca52-166a-92a3-966e85d4094e

Additional Considerations:

• Safe Mode: Booting your computer into Safe Mode loads Windows with only the essential drivers and programs. If the error doesn’t occur in Safe Mode, it suggests a problem with a recently installed driver or program.
• System Restore: If you recently made system changes (e.g., installed new software or updated drivers), consider performing a System Restore to revert your system to a point before the error started occurring.
• Hardware Diagnostics (if necessary): While less likely the sole cause, hardware issues can contribute to quota underflow errors. If none of the software solutions work, consult a qualified technician for hardware diagnostics and potential replacements.

Additional Resources:

• Microsoft article on troubleshooting Blue Screen errors: https://support.microsoft.com/en-us/windows/resolving-blue-screen-errors-in-windows-60b01860-58f2-be66-7516-5c45a66ae3c6
• How To Fix QUOTA_UNDERFLOW (0x00000021) error on Windows 10: https://www.youtube.com/watch?v=tZzZqCw1ILY

Remember: If you’re not comfortable with advanced troubleshooting steps, seek help from a qualified technician.