How to fix and resolve Windows 10 error 0xc000021a – Step by Step

In this article, we explain how to fix and resolve Windows 10 error 0xc000021a. The 0xC000021A error is a Blue Screen of Death or BSoD error (related: Blue Screen of Death guide) that occurs when a Windows user-mode subsystem is compromised.

Microsoft is known for sending regular updates to fix the bugs detected on the system. However, there are times when you would find the updates themselves causing a few issues. One such error that affected the operations during the initial days of Windows 10 was the BSOD or Blue Screen of Death syndrome 0xc000021a.

What is the 0xc000021a error?

Well, it is one of the types of the most dreaded Blue Screen of Death errors. When it strikes you, there will be a complete crash of your system, and you will be asked to restart your machine to resolve the issue. However, even after repeated restart attempts, you get back to the same error and cannot log again into your Windows 10 system.

The error will manifest itself in the following format.

You can get a host of other error indications as well. Some of them would include

  • STOP 0xC000021A
  • STATUS_SYSTEM_PROCESS_TERMINATED (Status System Process Terminated)
  • HALT: c000021a {Fatal System Error}
  • STOP c000021a

The error may be quite rare, which is exactly why you may not find it quite often. However, it can be one of the toughest ones to handle and get rid of the issue when it hits you.

What Causes the error 0xc000021a?

Ideally, the error would hit your system when you are updating the policy. It just prevents you from booting into your order when it hits you. It can be caused due to a variety of reasons. It may be possible to analyze the actual ideas and attempt to resolve the trouble.

Let us first check out the causes for the error so that we would be able to address them adequately. One of the Software or drivers may be misconfigured. It can stop the driver from loading correctly and cause the error. A damaged system registry can also create an issue and result in 0xc000021a failure.

Primary files that can cause this error an include

  • Exe – This file is responsible for the login and logout operations of your Windows system. It can get damaged due to a mistake in the update process or caused by third-party tools.
  • Exe – This is a file that belongs to a Microsoft server or client. If the fil is damaged, you can face the issue as above.

How to fix error 0xc000021a on Windows 10?

Several methods can help you resolve the error and get your system back in place. Let us check them out one by one.

Method 1 – Fix the corrupted files

As explained in the above discussion, corrupt files can be a huge issue. Fixing the corrupt files can be one of the right options in resolving the error. It can be set using the Windows installation media.

Insert your DVD and boot from it. If your device does not have a DVD drive, you may need to create a USB flash drive with the installation media. Once that done, follow the steps here below –

  • On the first screen you get access to, click on
  • Next, click on Advanced Options
  • In the next level, click on the option Command Prompt.
  • In the Command Prompt that comes up, type in the Command here and press ENTER.
C: /f /r

The system will begin checking your system for errors, and if it finds the errors, you will find that the files will be repaired by replacing them with the correct files on the installation media. If you get any confirmation option with a Y/N prompt, confirm with Y to continue with the process.

Method 2 – Use the Startup Repair option

The next best opportunity to resolve the error would be to use the Startup Repair tool. Follow the steps here below –

  • Boot Windows 10 DVD.
  • Click on Troubleshoot as in the above method.
  • Next, click on Advanced Options.
  • Click on Startup Repair.

The Startup Repair tool will begin repairing your files. Once the repair is done, remove the DVD and check if the issue has been resolved.

Method 3 – Run the DISM Command

Boot your computer into Safe mode. Once that done, you can run the DISM command to check if it can help you fix the BSOD issue.

Follow the steps here below –

  • Restart your computer and keep pressing F8.
  • Click on Troubleshoot -> Advanced Options -> Startup Settings -> Restart
  • Press the corresponding option to enter safe mode with “command prompt.”
  • In the command prompt that shows up, type in and enter the following command

dism /image:C: /cleanup-image /revertpendingactions

You can even use the following commands as well as

cd C:WindowsWinSxS

move pending.xml pending.old

Method 4 – Disable Driver Signature

Disabling the driver’s signature can help you take care of the driver compatibility issues. The system will be able to use the drivers that Microsoft does not sign.

Here is how you would resolve the issue –

  • Restart your computer.
  • Reach up to the Advanced Options following the steps as in the above discussion.
  • Click on Startup Repair
  • Choose the option for Disable driver signature enforcement

Click on Restart, and you should now be able to resolve the issue.

Method 5 – Run SFC

Boot into the Safe Mode as in the previous example. Run the Command Prompt in the safe mode by following the standard process.

Enter the following Command and press Enter.

SFC /scannow

This Command will scan all the system files on your system and repair any of the errors that it finds.

Reboot your machine, and the issue should ideally be resolved.

In Conclusion

The 0xc000021a error is quite an uncommon error. That is precisely why it may be a little difficult to resolve the error or find the right fixes that should help you determine the issue right away. However, we would assume that the tips and tutorials offered in the above discussion should help you eliminate the problem and fix and resolve Windows 10 error 0xc000021a.

It is most unlikely that you will face the issue in the latest versions of Windows 10, but in a rare case, if it affects you – you can try out the methods. Do use them and share which among the worked for you.

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