How To Fix 0xc000021a Error in Windows 10

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If you’re seeing an 0xc000021a error, you’re also seeing the Microsoft frown face and a Blue Screen of Death. Chances are that Windows just loops when you boot too so you can’t even get to the desktop to troubleshoot. While nobody likes to see a BSOD, as they are among the most frustrating sights in computing, the error isn’t fatal and can be overcome if you know how. So if you’re looking to fix 0xc000021a errors in Windows 10, read on.

There are a couple of things that can cause 0xc000021a errors. Windows files corruption after an update, a driver issue and a fault with either Winlogon.exe or Csrss.exe. All of which can be fixed relatively easily. Here’s how.

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Fix 0xc000021a errors in Windows 10

If you’re seeing 0xc000021a errors in Windows 10, you will also likely be in the reboot loop. So everything we’re going to do will need to be done from Safe Mode. The easiest way to get into Safe Mode is to boot your computer from installation media.

  1. Insert either your Windows 10 USB or DVD and set your computer to boot from it.
  2. When you see the Install now screen, click Repair your computer in the bottom left. This takes you to the Troubleshooting menu.
  3. Click Startup Repair and see if the process can automatically correct the problem.

If that doesn’t work, try this:

  1. Insert either your Windows 10 USB or DVD and set your computer to boot from it.
  2. When you see the Install now screen, click Repair your computer in the bottom left.
  3. Click Advanced options and then Command Prompt.
  4. Type ‘sfc /scannow’ and hit Enter. Allow the process to complete. If the System File Checker finds any errors, reboot your computer and retest.
  5. If no errors were found, type ‘dism /online /cleanup-image /restorehealth’. Allow the process to complete. If errors were found and corrected, reboot and retest.

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If that didn’t work, we need to fix the registry. We will make copies of your existing registry and then replace it with a new version. There is some risk in this process but if the preceding steps didn’t work, the next step is a system restore anyway so there is little to lose.

  1. Insert either your Windows 10 USB or DVD and set your computer to boot from it.
  2. When you see the Install now screen, click Repair your computer in the bottom left.
  3. Click Advanced options and then Command Prompt.
  4. Type C: and then ‘dir’.
  5. Type ‘cd \windows\system32\config’ and hit Enter.
  6. Type ‘dir’. You should see SYSTEM, SAM, DEFAULT, SECURITY, SOFTWARE and RegBack files.
  7. Type ‘copy *.* registry.old’. This will make a copy of your existing registry.
  8. Type ‘cd regback’ and Enter.
  9. Type ‘dir’. You should see You should see SYSTEM, SAM, DEFAULT, SECURITY, SOFTWARE and RegBack files. If they are present and have a file size greater than 0, the process will work. If the folders do not appear or are of 0 size, it will not work.
  10. Type ‘copy *.* ..’. Then type ‘a’ when prompted.
  11. Type Exit once the process is complete.
  12. Reboot your PC and retest.

This final step should most likely fix the issue if all other steps have failed. If, in the unlikely event it doesn’t fix the error, you are going to have to perform a system restore or fresh install.

Posted by Jamie on November 29, 2016

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