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How to Fix “The Application Was Unable to Start Correctly” 0xc000021a Error in Windows

Key takeaways:

  • The 0xc000021a error can occur due to corrupted system files, failed upgrades, or incomplete software installations
  • Common causes include incompatible external devices, corrupted hard drive sectors, outdated drivers, and malware
  • Solutions involve running system restore, uninstalling problematic updates, rebuilding BCD, and performing a clean Windows reinstall

The “0xc000021a” error, also known as the “The application was unable to start correctly” error, is a frustrating issue that many Windows users encounter. This error can prevent you from accessing your computer and cause a blue screen of death (BSOD). In this article, we’ll explore the common causes of this error and provide step-by-step solutions to help you fix it.

Understanding the 0xc000021a Error

The 0xc000021a error occurs when a user-mode subsystem, such as Winlogon or CSRSS, terminates unexpectedly. This can happen due to various reasons, including:

  • Corrupted system files
  • Failed Windows upgrades
  • Incomplete software installations
  • Incompatible external devices (e.g., USBs)
  • Corrupted hard drive sectors
  • Outdated or corrupted drivers
  • Malware or virus infections

When this error occurs, your computer may display a blue screen with the error code 0xc000021a and automatically restart, making it difficult to troubleshoot the issue.

Fixing the 0xc000021a Error

To resolve the 0xc000021a error, you can try the following solutions:

Solution 1: Run System Restore

If you have a recent system restore point, you can use it to roll back your computer to a previous state when the error did not occur.

  1. Boot your computer into Safe Mode
  2. Open System Restore by typing “rstrui.exe” in the Run dialog (Windows key + R)
  3. Select a restore point from before the error occurred
  4. Follow the on-screen instructions to complete the restore process

Solution 2: Uninstall Problematic Updates

If the error started occurring after a recent Windows update, uninstalling the update may resolve the issue.

  1. Boot into Safe Mode
  2. Open the Settings app and navigate to “Update & Security”
  3. Click on “View update history” and then “Uninstall updates”
  4. Locate and uninstall the problematic update
  5. Restart your computer

Solution 3: Rebuild the Boot Configuration Data (BCD)

Rebuilding the BCD can help resolve startup issues, including the 0xc000021a error.

  1. Boot from your Windows installation media
  2. Select “Repair your computer” and then “Troubleshoot”
  3. Choose “Command Prompt” and enter the following commands:
bootrec /fixmbr
bootrec /fixboot
  1. Restart your computer

Solution 4: Perform a Clean Windows Reinstall

If none of the above solutions work, performing a clean Windows reinstall may be necessary.

  1. Back up your important data
  2. Boot from your Windows installation media
  3. Follow the on-screen instructions to reinstall Windows
  4. Restore your backed-up data

Preventing the 0xc000021a Error

To minimize the risk of encountering the 0xc000021a error in the future, consider the following:

  • Keep your Windows system and drivers up to date
  • Regularly scan your computer for malware and viruses
  • Avoid installing software from untrusted sources
  • Safely eject external devices before removing them
  • Perform regular system maintenance (e.g., disk cleanup, defragmentation)

FAQ

What is the 0xc000021a error?

The 0xc000021a error is a Windows error that occurs when a user-mode subsystem, such as Winlogon or CSRSS, terminates unexpectedly. This error can cause a blue screen of death (BSOD) and prevent you from accessing your computer.

What causes the 0xc000021a error?

Common causes of the 0xc000021a error include corrupted system files, failed Windows upgrades, incomplete software installations, incompatible external devices, corrupted hard drive sectors, outdated or corrupted drivers, and malware or virus infections.

How can I fix the 0xc000021a error?

You can try fixing the 0xc000021a error by running System Restore, uninstalling problematic updates, rebuilding the Boot Configuration Data (BCD), or performing a clean Windows reinstall.

Can I prevent the 0xc000021a error from occurring?

While it’s not always possible to prevent the 0xc000021a error, you can minimize the risk by keeping your Windows system and drivers up to date, regularly scanning for malware and viruses, avoiding software from untrusted sources, safely ejecting external devices, and performing regular system maintenance.

What should I do if none of the solutions work?

If none of the provided solutions work, it’s recommended to seek assistance from a professional technician or contact Microsoft support for further guidance.

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