How to Fix Windows Error Code 0xc000021a [Solved]

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Windows Error Code 0xc000021a is a severe system execution crash that occurs when a vital user-mode subsystem component fails to initialize properly. This critical error triggers an immediate Blue Screen of Death (BSOD) because Windows cannot guarantee data security when its core background file verification systems stop working.

Whether this system crash stems from mismatched file signatures following an interrupted operating update or conflicting security program background tasks, you can clear it. Follow this step-by-step troubleshooting guide to bypass error 0xc000021a and recover your desktop screen.

Common Causes of Error Code 0xc000021a

• Mismatched Winlogon or Csrss Files: Vital system file signatures corrupted during a background update cycle.
• Enforced Driver Signature Failures: Third-party hardware programs loading unsigned files that trigger system security blocks.
• Broken Software Registry Keys: Damaged interface instructions preventing Windows from loading your user profile.

Method 1: Boot into Safe Mode and Uninstall the Most Recent System Update Patch

If an automated software patch drops corrupted files into your operating directory, your computer will loop on startup. Booting into Safe Mode allows you to roll back the broken patch safely.

  1. Turn your PC off completely, turn it back on, and hold the physical power button down as soon as the logo appears to force a hard shutdown.
  2. Repeat this hard shutdown process three times until your computer loads the blue Automatic Repair environment.
  3. Navigate through Troubleshoot > Advanced Options > Startup Settings and click the gray Restart button.
  4. Press the number 4 or F4 key on your keyboard to command Windows to boot inside its secure Safe Mode directory.
  5. Open Settings > Windows Update > Update History, scroll down to select Uninstall Updates, and remove the latest patch file.

Method 2: Disable the Enforced Driver Signature Verification Security Grid

When older peripheral hardware controllers try to communicate with modern Windows security architectures, signature mismatch blocks can crash the system. Temporarily bypassing this check restores execution tasks immediately.

  1. Force your computer into the Automatic Repair environment again by interrupting the boot process three times using your power button.
  2. Select Troubleshoot from the main repair screen layout and open the Advanced Options sub-menu panel.
  3. Click on the Startup Settings option and click the blue Restart button located in the bottom-right corner.
  4. Press the number 7 or F7 key on your keyboard to select the option labeled Disable driver signature enforcement.
  5. Allow your computer to boot up automatically into your regular desktop screen and check for any outdated hardware drivers.

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