
Fixing the Blue Screen Error “0xc000021a” in Windows
The 0xc000021a error is one of numerous Blue Screen of Death errors affecting all Windows operating system versions. STOP 0xC000021A, STATUS SYSTEM PROCESS TERMINATED, HALT: c000021a – Fatal System Error, and STOP c000021a are all representations of the same thing. It’s followed by a warning saying that Your PC has encountered a problem and has to restart in Windows 10.
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Many customers have reported seeing this error message after upgrading to a newer version of Windows 10. When attempting to boot into Windows, it generally appears on the screen, making it difficult to resolve this BSOD error using only the BIOS and Advanced Startup mode tools.
As a result, you may be tempted to seek expert assistance. However, following the simple procedures below, you won’t need it to fix problems comparable to the Inaccessible Boot Device error.
What Causes the Microsoft Windows Blue Screen Error 0xc000021a
Most users who encounter the Windows error code 0xc000021a are upgrading or have just finished upgrading to a newer version of Windows. Users are unable to boot their computers due to the BSOD problem properly.
There are several reasons for this problem. One of the most common reasons is that the devices in your peripherals or external devices plugged into the system are causing interference with starting the system. Additionally, several important system files needed to operate the system may be missing or corrupted, driven mainly by a failed Windows update or a virus infection.
Here are other causes of the Windows Error 0xc000021a and other critical system errors:
- Misconfigured Windows registry entries
- Corrupted files
- Misconfigured driver signature enforcement feature settings
- Important Windows files are missing from the Windows installation media
- Incompatible software program installed in the system
Troubleshooting Methods to Fix the Stop Code 0xc000021a Error
The Windows OS error 0xc000021a prevents you from accessing the system. We will work on your computer in Safe Mode if you wish to go back into it without installing a fresh copy of Windows.
The safe mode of an operating system is a troubleshooting mode that can be used on a computer. The safe mode of an operating system is designed to help fix the majority of issues that can arise if not all of them. It is also extensively used for uninstalling malicious software, particularly security programs.
Here’s how you can access Safe Mode:
- To access the Advanced boot options, press the power button under the Start Menu’s cog icon.

- In the start submenu, hold the Shift key and press Restart.
- Wait for the system to boot into Windows Boot Menu. Click on Troubleshoot > Advanced Options > Startup Settings and tap on the Restart button.

- Once the restart has finished, you will be greeted with the Startup Settings menu. In there, press 4 to enable safe mode. Alternatively, you can enable the safe mode with networking by pressing 5, and it’s generally better to go with option five here.

- Once your computer is in Safe Mode, we can start troubleshooting.
First Method – Run the Windows Startup Repair
Startup repair, also known as Automatic Repair in older versions of Windows, is a built-in diagnostic tool in Microsoft Windows intended to promptly resolve the most frequent problems that keep your device from starting up in the operating system.
- Press the Shift key on your keyboard and simultaneously press the Power button.

- You need to continue holding down the Shift key while waiting for the machine to power.
- Once the computer starts, you’ll find a screen with a few options. Click Troubleshoot.
- Next, click on Advanced options.
- In the Advanced options menu, choose Startup Repair.

- Once the Startup Repair screen opens, choose an account. Be sure to use an account with Administrator access.
- After entering the password, click Continue. And wait for the process to complete.
- Reboot your PC and confirm if the stop code 0xc000021a has already been fixed.
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Second Method – Scan Your System with the System File Checker
Windows SFC is a utility that checks for any damaged or missing files. The SFC checks the integrity of all protected system files and replaces outdated, corrupt, or changed ones with newer copies. This procedure may be used to repair corrupted update files causing the 0xc000021a error.
- While in Safe Mode, press “Windows,” press “R,” and type “cmd” in the run command line. Hold down the “ctrl and shift” keys together and hit enter to select Command Prompt. Enter the next window to grant administrator permissions and open the Command Prompt window.
- When the command prompt appears, type “sfc /scannow” and enter. SFC will now check for corrupted Windows update files. Wait for the SFC to complete the scan and restart the computer. Once done, run the Windows 10 Update tool to check if the issue has been fixed.

- Once the System File Checker scan is complete, boot Windows manually. Run the Windows update tool and check if this method finally fixed the Windows 10 error 0xc000021a.
Third Method – Uninstall the Last Application You Installed on Your Computer
Some software or apps can cause conflicts with your computer, resulting in Blue Screen errors like the 0xc000021a. We strongly advise you to uninstall the most recent application you downloaded and installed if you get this issue, as corrupt files may have come together with the program. We’ll eliminate Visual C ++ in the following examples, and the same procedures should be followed for any additional applications or programs.
- Hold down the Windows + R keys on your keyboard, type in “appwiz.cpl” on the run command line, and press “enter.”
- In the list of applications, look for the currently installed version of Visual C ++ and click uninstall.

- After uninstalling Visual C ++ Redistributable for Visual Studio from your computer, download the latest version of Visual C ++ Redistributable by clicking here.
- Make sure to download the latest setup file and the appropriate version for your computer and follow the on-screen instructions when installing the program.
- Restart your computer as usual and see if you can go to your regular Windows desktop and confirm if the Blue Screen error 0xc000021a has already been fixed.
Fourth Method – Disable Driver Signature Enforcement
Unsigned drivers are not allowed to run on Windows by default. So, if you just installed drivers from a source other than Microsoft, your operating system won’t start up because of Driver Signature Enforcement. As a result, the 0xc000021a error occurs.
- Access the Advanced boot options by pressing the power button under the Start Menu’s cog icon.

- In the start submenu, hold the Shift key and press Restart.
- Wait for the system to boot into Windows Boot Menu. Click on Troubleshoot > Advanced Options > Startup Settings and tap on the Restart button.

- Once the restart has finished, you will be greeted with the Startup Settings menu. Press number 7 to boot into the Windows OS with Disable Driver Signature Enforcement.

Fifth Method – Perform a Clean Boot
If you can’t figure out what’s causing error 0xc000021a, you might want to try a clean boot. A third-party program or launching processes are usually at blame for the problem. It is possible to identify the problem by disabling all startup applications and then re-enabling them.
- Boot your computer into Safe Mode using the steps we listed in the method mentioned above.
- On your keyboard, press the Windows + R key.
- Once the run dialog box appears, type “msconfig” and click OK.

- In the System Configuration window, Locate the Services tab section and check the Hide all Microsoft services box.
- Click on the Disable all button and then select the Apply button.

- Next, go to the Startup tab and select the Open task manager link.
- Choose startup programs one by one and then select the Disable button.

- Restart your computer and check if the Windows error 0xc000021a has been fixed.
Sixth Method – Perform a System Restore
System Restore is a feature in Windows that lets users restore their system to an initial state, which can help recover from system failures or other issues. This method will remove all the files in your Windows system, including personal files. We strongly suggest performing this step if you already have a backup of your files.
- Download Media Creation Tool from the Microsoft website.

- Run Media Creation Tool to create a Windows installation media (You can use a USB installation drive or CD/DVD).
- Boot the PC from the disc or USB drive.
- Next, configure the language, keyboard method, and time. Click Repair your computer.

- Go to Choose an option. Choose Troubleshoot and Advanced options. Last, choose System Restore.
- Follow the wizard to finish a system restore.

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Frequently Asked Questions
What does stop code 0xc000021a mean?
The 0xc000021a stop code indicates that a critical error has occurred in the Windows kernel. Corrupt system files usually cause this. To fix this problem, you must use a Windows 10 repair tool to fix the corrupt files.
What causes Windows 10 Stop Code 0xC000021A?
The Windows 10 Stop Code 0xC000021A error is caused by a corrupt or missing boot configuration data (BCD) file. This file is responsible for storing information about the operating system’s boot process, and when it becomes corrupted or is missing, the system cannot boot properly.
There are several ways the BCD file can become corrupted, including errors during the Windows installation process, hardware failures, and software conflicts.
How do I fix Windows stop code registry error?
If you see a stop error code after upgrading Windows, it’s likely due to a corrupted registry. To fix this, you’ll need to run the Registry Repair tool, which will scan your registry and attempt to repair any corruption.
What causes 0xC000021A?
A failure in the user mode subsystem causes the 0xC000021A error. This can happen when upgrading to a new Windows version or when an incomplete installation is present. In either case, the result is that the system cannot run properly.