How To 

How to fix Windows 10 error 0xc000021a


The Windows 10 error 0xc000021a is a bug check error that usually includes ‘STATUS_SYSTEM_PROCESS_TERMINATED’. It can result in a BSOD and even a boot loop that is difficult to break out of without booting into safe mode. If you need to fix Windows 10 error 0xc000021a, I can help.

The error occurs when either WinLogon or Client Server Runtime Subsystem (CSRSS) presents an error or is corrupted. Windows thinks it has been hit by malware or security is otherwise compromised and stops booting. There are a couple of things we can do to fix the error before having to perform a system reset or restore.

Fix Windows 10 error 0xc000021a
To address this error, we need to use our old friends sfc /scannow or DISM. If you cannot boot into the desktop to access CMD, boot into safe mode using install media and select ‘Safe Mode with Command Prompt’ from the options.

1. Open a CMD window as an administrator.
2. Type or paste ‘sfc /scannow’ and hit Enter.
3. Allow the process to complete and make any repairs.

If the error still occurs, try DISM.

1. Open a CMD window as an administrator.
2. Type or paste ‘dism/online/cleanup-image/restorehealth’ and hit Enter.
3. Allow the process to complete and make any repairs.

Finally, we can disable driver signature enforcement which may help.

1. Boot your computer into Safe Mode and select Troubleshoot.
2. Select Advanced Options, Startup Settings and Disable Driver Signature Enforcement.
3. Restart and retest.

This stops Windows thinking unsigned drivers are corrupted or insecure. It has been known to fix Windows 10 error 0xc000021a.

If none of those procedures fix the file mismatch, you have two options. Perform a system restore or a reset as you see fit. If they don’t work, it’s time for a system restore!

More Windows 10 troubleshooting tips that may help:
How to get into advanced startup options in Windows 10

How to perform a repair installation for Windows 10
How to uninstall and reinstall Windows 10 built-in apps


 

ASK THE COMMUNITY