The recent versions of Windows like Windows 8 and Windows 10 have done a lot to reverse the impression of Microsoft operating systems as being crash-prone, but even these newer and much more stable operating systems can still crash. One particularly annoying Windows error is error number 0xc000021A.

This error message is one of the errors that means Windows itself has crashed, and your computer needs to restart. If you get this error, a big blue screen appears, telling you it’s collecting some error information and will then restart your computer for you. In small print under that, it gives the error code, 0xc000021A, and tells you that you can find out more information about the error online.
Don’t panic! This error can be corrected so it won’t recur to bother you again. It’s most common for this error to occur after a Windows update.
Repair Windows Yourself
Since your Windows computer isn’t functioning normally, you’ll have to boot Windows manually.
- To do that, hold down the “Shift” key on your keyboard while you select “Restart” from the power options for Windows. You may need to use a bootable Windows disc or bootable Windows USB drive if you can’t access the “Restart” function.
- A blue option screen should load that says, “Choose an option.” Select “Troubleshoot.”
- In the Troubleshoot screen, select “Advanced Options.”
- Next, in Advanced Options, select “Startup Settings.”
- On the Startup Settings Screen,select “Disable driver signature enforcement” by pressing “F7” on your keyboard.
- Press “Enter” on your keyboard or the “Restart” button if one’s displayed.
Your computer will restart the way you’ve told it to. You can adjust your computer by using the different selections offered until you find the one that works for you.
Let Windows Repair Itself
Alternatively, you can choose the “Startup repair option,” where Windows automatically scans your computer to locate the problem.
- Hold down the “Shift” key on your keyboard while you select “Restart” from the power options for Windows. You may need to use a bootable Windows disc or bootable Windows USB drive if you can’t access the “Restart” function.
- A blue option screen should load that says, “Choose an option.” Select “Troubleshoot.”
- In the Troubleshoot screen, select “Advanced Options.”
- Next, select “Startup Repair,” which scans and tries repairing your computer automatically.
Hopefully, Windows has found and repaired the problem that was causing your computer not to boot correctly.
Files That Cause Error “0xc000021A”
The two files that are responsible for the “0Xc000021A” error are “winlogon.exe” and “csrss.exe.” The first file is in charge of logging in and out of Windows, as the name suggests. The second file is a Windows server or client file. If either of these two files gets damaged or corrupted, the error can occur.
Windows can repair corrupted files and find missing files, but it can’t repair and fix hardware issues.
I hope this helped you resolve your Windows logon error without having to resort to resort to doing a clean install of Windows 8 or 10.
If you have found other ways to resolve this error, please let us know in the comments!
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23 thoughts on “How to Fix Error 0xc000021a in Windows 8 & 10”
Be patient… it does take a little time…. but it fixed my problem.
My Solution was to go to device manager (if you can) and uninstall all display adapters and tick ” delete the driver soft ware for this device”. Go to manufactures site and download the latest drivers for you graphics card. In my case it was Nvidia GeForce.
Right click “This PC” in windows explorer, click on properties, then Advance System Settings, then the Hardware tab. Then choose “Device Installation Settings “. Now click ” No ( your device might not work as expected) then click on Save Changes. Now install your up to date drive you downloaded.
Hope this helps someone as it is annoying and very time consuming trying to find a resolution for this.
Your mileage may vary. TGF Macs.
It’s pretty simple and for some people hard to deal with, but it could easily be a hardware issue. Technology isn’t like art, you can’t keep doing the same things and expect different results. If you’ve run the recommended troubleshooting steps (from what I’ve read this article does a good job explaining the issue and what to do) and you’re still running into issues, then I would suggest the same thing as the article and say that it is more than likely a hardware issue.
I’ve been reading up on the error and from what I’ve found it is not only related to winlogon and csrss. The issue can also be caused by a faulty CPU or RAM dims. I would also assume (based on personal experience with RAM and CPU issues) that it could be a faulty HDD with read/write errors.
I can assure you the information provided in this article is not useless and does fix the problem in certain situations. I hope this helps.
OS.
Tony W
I have been getting the same error code. I have a windows 8. I don’t have my disc either. My laptop asked to updated to windows 10, I tried to update it but it was not compatable. I have tried all of these options and non work. It’s a constant loop. I don’t know what to do anymore. Any advice that will be successful?
The increasing recency of our posts suggests the latest Windows update has screwed something up enormously, or we’ve all fallen foul of the same super-smart malware.
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