0xC000021A Windows 8.1 Won’t Boot (aka FU Windows Update)

If you’ve searched for 0xC000021A, chances are you’ve recently started your computer after some updates have “applied” and you’ve been greeted with a stupid blue screen with 0xC000021A and now you’re stuck in a boot loop. Yeah?

This is because of Windows Update, for some reason an update has broken something and caused a problem with the Windows boot process. I’m fairly certain this update is a specific one, possibly for Windows 8.1 Pro as this issue occurred on my main PC and also Surface Pro 3 but not my laptop – yet. Anyway, thankfully it’s a relatively simple fix.

Remember that recovery disk you made? You’ll need that, or because I don’t know many people who have a recovery disk, you’ll need a Windows 8.1 CD or another Windows 8.1 computer and a free USB drive.


Update: Added image of possible updates causing.


What you need to to is load up your recovery media.
For a recovery disk you need to go to troubleshoot -> advanced -> Command Prompt.
For a CD after choosing a language you need to go to “Repair my PC” and you’ll be given a command prompt.

Now enter this command:

If you get an error that the image cannot be found, you might need to change the drive path as sometimes during the installers C:\ isn’t the main drive. To list all the drives attached to your device use this command:

X: usually represents the recovery media you are using.
If you still don’t quite know which of these drives you need you can use this command to list the contents of a drive:

Obviously a Windows drive will have the “Windows” and “Program Files” folders. etc.

Once you’ve got that command sorted, you can close the command prompt and turn off you PC, remove the recovery media and start as usual without the stupid blue screen.

NOTE: If you’re doing this on a Surface, you MUST have a bootable USB drive, not a CD. You can make a recovery drive from any other Windows 8.1 computer which will work fine for this.

 UPDATE 18 Jan 2015:

I’ve taken a screenshot of the recent failed updates I’ve had on my system, looks to be one of the following.
Screenshot 2015-01-17 11.10.41I’ve also contacted MicrosoftSupport about the issue, so far they’ve told me to try installing the updates on a clean boot which did nothing.