What is Error code 0xc000021a?

Error code 0xc000021a occurs when the system is unable to start or there’s a failure in critical system processes. Normally, it would take about several seconds for the system to boot and while on the startup process, error code 0xc000021a may take place to block the system to boot up. Users will get a blue screen of death (BOSD) when this error occurs.

Error Causes

There are several reasons why error code 0xc000021a occurs. It is important to have full understanding of what caused the blue screen of death before attempting to fix the error by yourself. See below for a few common causes:

• Computer malware has infiltrated your device.
• Important files such as Winlogon.exe and Csrss.exe are damaged. Winlogon.exe file is responsible for handling the login and logout processes while Csrss.exe is a vital part of Microsoft Client or Server ‘Runtime Server Subsystem’. Once one of these files are damaged or deleted, the stop error will occur.
• When there are mismatched system files installed or system upgrading process failed or still incomplete.
• Premature unloading of Wbemprox.dll
• Newly installed third-party software is not compatible with the operating system.
• There are corrupted, outdated, or incorrectly configured device drivers.
• There’s an insufficient space in system partition. Once the system partition is full, certain errors such as error code 0xc000021a will manifest.
• Windows registry is corrupted or damaged due to a software or system change. This means there are registry entries that are not cleared after uninstalling an application.

Further Information and Manual Repair

In fixing error code 0xc000021a, you might want to try and manually do so. Manual repair methods can give users effective and efficient solutions, addressing the root problems in relation to Windows error codes. Once the manual repair method is correctly implemented, users will be able to resolve issues immediately.
However, there might be instances when a Windows professional is needed. In such cases, seek help from a certified Windows expert or you might want to consider using an automated tool whenever necessary.
Method One: Convert the Drive or Partition from NTFS to GPT
In order to fix Error code 0xc000021a in Windows 10, you might need to convert the partition or drive from NTFS to GPT. See below for the procedure:
1. Shut down your device then put in the Windows installation USB key or DVD.
2. Boot your device to the USB key or DVD in UEFI mode.
3. Inside the Windows Setup, open a Command Prompt window by pressing Shift + F10.
4. Type diskpart in the Command Prompt window to open the diskpart tool.
5. Type list disk to identify which drive to reformat.
6. Select which drive to reformat by typing select disk in the command prompt. Afterwards, type clean then hit Enter. Once done, type convert gpt to be able to convert the drive from NTFS to GPT. Finally, type exit and press Enter. You can now close the Command Prompt window.
7. Once the partition or drive is converted from NTFS to GPT, user can now continue the Windows Setup installation.
NOTE: Select Custom in choosing which installation type to use. The drive will then appear as a single area of unallocated space. Choose that unallocated space then select Next. At this point, Windows will now begin the installation.

Method Two: Fix System File Errors

There are times when system files get corrupted or damaged which will result in system failure. If this is the case, you can use a Windows free tool to repair corrupted or damaged system files.

1. Right click on the Start button then select Command Prompt (Admin) from the list to open a Command Prompt window.
2. Once the Command Prompt appears, type sfc /scannow then hit Enter. Wait until the process completes. If the process is completed and it doesn’t report any error or issues remain unsolved, you might want to employ the next method.

Method Three: Reset Windows 10

Resetting Windows will delete all software and user accounts installed in the operating system and will reinstall a fresh Windows.

1. Boot your device using Windows installation USB key or DVD. Select Repair your computer to locate the Troubleshoot option. Afterwards, choose Reset this PC.
NOTE: If the device is able to boot the system, you can reset Windows without using Windows installation USB key or DVD. You just have to boot the device then navigate to Settings in the Start button. Choose Update & Recovery then select Recovery found on the left pane. Choose Reset this PC option then select Go back to an earlier build and Advanced startup. Select Get Started button found in the Reset this PC tab.

2. Depending on your device’s condition, you can either select Keep my files or Remove everything. Both options will remove all applications installed in the device and will revert to default settings.
3. Choose either Just remove my files or Remove files and clean the drive depending on the situation. If you choose Remove files and clean the drive option, procedure will take longer as it will erase all the files permanently. In this case, deleted files cannot be recovered. However, if you don’t want to remove files permanently, select Just remove my files.
4. Once you’ve decided how to reset your system, click on Next once the Warning screen appears. Afterwards, choose Reset once prompted. When the process completed, click on Continue.

Method Four: Download an Automated Tool

Can’t seem to put up with the long and technical manual repair process? You can still fix this error by downloading and installing a powerful automated tool that will surely get the job done in a jiffy!