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Error Code 0xC000021a | Simple And Easy Ways To Fix It

Error code 0xC000021a one of the well-known Windows errors which appears more often than not on every version of Windows OS. Basically, this error is a blue screen of death or BSOD error. It primarily occurs after restarting your device. If this error strikes to your device, the system is unable to start. More specifically, this Windows error appears when Windows processes can’t work properly, such as Winlogon.exe and Csrss.exe stops running. If you face this error, don’t panic. It is very much possible that you will be able to eradicate this stop code 0xC000021a error by yourself and on time. But for that, having clear and compact instructions is imperative and that is exactly what you will get in this article. You can easily resolve this error with the help of proper technical information. If you are unable to solve this issue until now, then read this article thoroughly.

Know the Possible Causes for Error Code 0xC000021a

There are so many major as well as minor reasons, which resides behind this error code 0xC000021a. Below we have the complete list of those causes.


  • Installation of outdated software
  • Improper operations on the system
  • Winlogon.exe or csrss.exe is damaged
  • Corrupted Windows registry files
  • Wbemprox.dll library is unloaded prematurely
  • Alteration of registry files
  • Insufficient space in the system partition
  • Incomplete installation of Windows version
  • Mismatch of the system files
  • Improper setup of software or driver
  • Virus/malware infections to the system.


Now, here a major question arises that what are the symptoms when the issue occurs. Let’s focus on that.

Common Symptoms of Error 0xC000021a

Error code 0xC000021a is well known to the users and can be encountered often. Below we have some of the major symptoms by which you can identify that stop code 0xC000021a has infiltrated into your system.


  1. The error appears and crashes the current running program’s window.
  2. The frequent crashing of the system will be a common thing.
  3. The error message displays on the screen that says:

“STOP: c000021a {Fatal System Error}.The Windows SubSystem system process terminated unexpectedly with a status of 0xc0000005. The system has been shut down”.

  1. The slow reaction of the mouse and keyboard is also a symptom.
  2. Performance degradation of the Windows 8/10 PC.
  3. Sudden freezing of the system for a few seconds.

Apply these Hacks to Resolve Windows Stop Code 0xC000021a

In this section, we have provided some effective solutions to troubleshoot this issue. Let’s check out the hacks attentively:

For Windows XP Users:


Below we have listed the solutions to fix the error code 0xC000021a on a Windows XP computer. Go through them and apply them one by one, until you get the issue fixed.

Fix 1: Boot into Last Known Good Configuration

The first thing you have to do is boot the system into the ‘Last known good configuration mode’. This mode helps you to save the previous version of Windows Registry. So, go through the below directions one by one:


  1. First of all, reboot the system and wait for a while.
  2. Then, tap the F8 key.
  3. When a list of boot options appear on the screen, release the key.
  4. Now, click on the ‘Last Known Good Configuration’ option.
  5. Next, hit the Enter button.
  6. Wait for sometimes and check the system for this error code 0xC000021a.

Fix 2: Uninstall Installed Software or Driver

If this issue occurs after installing new software or hardware driver or new installation of your Windows XP, you need to boot into the Safe Mode and then uninstall it. So, follow the steps below:


  1. At first, restart your device.
  2. Then, press the F8 button.
  3. When the Windows XP logo displays, release the F8 key.
  4. Next, go to the Windows Advanced option and choose ‘Safe Mode’.
  5. Hit the Enter button.
  6. Finally, check if the problem is resolved or not. If not, then go through the next solution.

Fix 3: Run System Restore

You can fix this error code by performing the System Restore. To do that, try to follow these guidelines provided below:


  1. Restart the computer and hit the F8 button.
  2. Then, click on the ‘Windows Advanced Options’ menu.
  3. Now, choose ‘Safe mode with Command prompt’ using the Arrow keys.
  4. Press the Enter key and log in as Administrator.
  5. When the Command Prompt appears on the screen, type the following command:


  1. Tap on the Enter key and follow the on-screen instructions to complete the restoration process.

For Windows Vista and 7 Users:


If you happen to be a Windows Vista or Windows 7 user, you need to follow the methods as stated below.

Fix 1: Uninstall Previously Installed Software or Driver

If you recently installed new software or driver on your system, boot into Safe Mode and uninstall it. So, take a look below:

  1. Firstly, reboot your device.
  2. After that, click on the F8 button.
  3. When the Windows Vista logo displays, leave the F8 key.
  4. Next, click on the ‘Advanced Boot’ option and select ‘Safe Mode’.
  5. Lastly, hit the Enter button.

Fix 2: Use Startup Repair

You can resolve this error code by running the Startup Repair Utility with the Windows Vista or Windows 7 installation disc (DVD). To use System Repair, follow this way:


  1. First of all, take the original DVD with your Windows version and press any key to boot from the DVD.
  2. When the Welcome screen appears, select ‘Repair your computer’.
  3. After that, choose the Operating System and select ‘Next’.
  4. When the System Recovery Options displays on the screen, click on the ‘Startup Repair’ option from the System Recovery section.
  5. Hold on for the process to be finished.
  6. Lastly, restart the system and check if the issue is fixed or not.

Fix 3: Last Known Good Configuration

Booting into the last known good configuration mode help you to fix the issue. So, take a look below:


  1. Firstly, restart the system and wait for a while.
  2. Then, click on the F8 button repeatedly.
  1. When a list of boot options display on the screen, leave the key.
  2. Now, select the ‘Advanced Boot’ and click on the ‘Last Known Good Configuration’ option.
  3. Next, hit the Enter button.

Fix 4: Disable Services in Msconfig

When you start your Windows Vista or 7 system, if the 0xC000021a error shows due to a software or driver that runs with the Windows startup, you can try and turn off the Services enlisted in the System Configuration (msconfig) utility:


  1. First of all, click the Windows and R key together on your keyboard.
  2. Then, write ‘MSConfig’ there and hit the Enter key.
  3. Now, select the services tab and check if all Microsoft services are hidden or not.
  4. When you see Disable All click option, select Apply.
  5. Now, go to the startup tab and choose Open Task Manager.
  6. After that, turn off all the startup programs one by one.
  7. Next, click OK and close the Msconfig window and restart your computer.

Fix 5: System Restore

If this error code appears due to an incompatible software or driver, then you need to restore your device as early as possible. So, you have to enable System Restore on the system. That helps to install any software or driver. So, follow these steps to perform a System Restore in a Safe Mode.


  1. Reboot the system.
  2. Next, tap on the F8 button.
  3. Then, select the ‘Advanced Boot’ option.
  4. After that, click on ‘Safe mode with Command prompt’ using the Arrow keys.
  5. Now, hit the Enter key and log in as Administrator.
  6. When the Command Prompt shows on the screen, type the following command:


  1. At last, follow the on-screen directions.
  2. Now, check if the issue persists or not. If yes, then go for the next hacks.

Fix 6: Last Restore Point by Command Prompt

If the above trick fails to work, then you can recover the restore point by running the ‘dism’ command using Command Prompt. So, follow these steps one by one:


  1. Firstly, hit the F8 key and go to the Windows Advanced option.
  2. Choose ‘Repair your computer’.
  3. Click on Enter. If Repair option isn’t there, then you need to use Installation disc.
  4. Then, open the System Recovery option and select ‘Command Prompt’.
  5. Write the following command and hit the Enter button.

‘dism /image:C:\ /cleanup-image /revertpendingactions’

  1. Make sure to replace C: with the letter of the driver where your Windows Vista or Windows 7 is installed.

For Windows 8, 8.1 and 10 Users:


If you are a user of Windows 8, 8.1, or 10, then the methods to follow to fix the error code 0xC000021a are as provided below.

Fix 1: Clean Boot

This is one of the easiest ways to resolve this matter with ease. So, go through the steps below:


  1. First of all, click on the Start menu.

  2. Then, click on Windows and R keys both.

  3. After that, type ‘Msconfig’ in the Run dialog box.
  4. Now, press Enter and go to the General option at the System Configuration Windows.
  5. Choose ‘Selective Startup’ and uncheck the Load Startup items.
  6. Next, open the ‘Services’ tab and mark the ‘Hide all Microsoft Services’ option.
  7. Click on the ‘Disable all’ option and select ‘Startup’.
  8. Turn off all the services by right-clicking on it and choose ‘Disable’.
  9. Lastly, reboot your device.

Fix 2: Run the DISM Tool

This troublesome issue is probably caused by the corrupted Windows update files. If such is the case, you can resolve it easily by running the ‘Deployment Image Servicing and Management’ or DISM tool. To run this tool, follow the below guidelines one by one:


  1. Firstly, press and hold the Windows logo key and the R key both on the keyboard. It will open the Run dialog window.
  2. Then, type ‘cmd’ or press the Shift, Ctrl and Enter key together to run the Command prompt section as an Administrator.
  3. After that, you will be asked for permission. Press YES to run it.
  4. Next, type the following command:


“Dism /Online /Cleanup-Image /ScanHealth”

   And, press the Enter key.


This command helps to scan all the system files and verifies whether the files are official or not. But, this doesn’t prevent corruption. It will take a few minutes to complete.


  1. Then, type “Dism /Online /Cleanup-Image /CheckHealth” and press the Enter key. It will check whether the Windows 10 image of your device is corrupted or not.
  2. After completing, type this command “Dism /Online /Cleanup-Image /RestoreHealth”. This command helps to repair the corrupted files. It will replace the corrupted files with the secured ones.
  3. Now, wait for a couple of minutes and then, close the Command Prompt.
  4. Finally, check if the problem is totally resolved or not.

Fix 3: System Restore

Another method is System restore to fix this issue quickly.  So, you need to follow these steps:


  1. At first, go to the search bar.
  2. Then, type ‘Create a Restore point’.
  3. Now, select the item which appears on the screen.
  4. After that, choose the ‘System Protection’ option, and click on the ‘System Restore’ option.
  5. Select the ‘Next’ option.
  6. Next, you should see a list of all the available restore points.
  7. Choose the most recent restore point.
  8. Then, select the Next option again and click on the Finish option.
  9. After selecting, it will run automatically. Wait for sometimes to finish this process completely.
  10. Finally, check whether the issue is fixed or not.

Fix 4: Disable Driver Signature

If the issue still appears, then drivers that stop loading at startup can cause this problem. To turn off the driver signature, go through the following directions:


  1. First of all, open the Start option and press the Shift key.
  2. Then, hold on the Power button.
  3. Choose ‘Restart’.
  4. In the Recovery options menu, select Troubleshoot.
  5. Choose Advanced options.
  6. Now, select Startup settings and click on Restart.
  7. After restarting PC, press F7 to select Disable driver signature enforcement.
  8. Insert the installation media and look for changes.

Fix 5: 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. Just look at the following steps carefully:


  1. Shut down your device and then, put in the Windows installation USB key or DVD.
  2. Then, boot your device to the USB key or DVD in UEFI mode.
  3. After that, open the Windows Setup and open a Command Prompt window by pressing Shift and F10 button.
  4. Type ‘diskpart’ there to open the diskpart tool.
  5. Also, type list disk to identify which drive to reformat.
  6. After that, type clean and hit Enter.
  7. Once done, type convert gpt to be able to convert the drive from NTFS to GPT.
  8. Finally, type exit and press Enter. You can now close the Command Prompt window.
  9. After converting the partition from NTFS to GPT, you can continue the Windows Setup installation.

Fix 6: Run the System File Checker

The SFC scan or System File Checker helps to replace or repair the corrupted files. If you notice that the error still strikes after converting the drive, then this method may resolve this issue. To complete the SFC scan, you need to follow the steps cited below:


  1. First of all, right click on the Start icon.
  2. Go to the Command Prompt section.
  3. Now, type ‘sfc/scannow’ and press the Enter key on the keyboard.
  4. After that, the SFC scan will scan your device. Make sure that you don’t cancel the scan process until it gets complete. After scanning, it will show the corrupt files of your device.
  5. After scanning, if there are any corrupt files in your device, type this command:

“findstr /c:”[SR]” %windir%\Logs\CBS\CBS.log >”%userprofile%\Desktop\sfcdetails.txt.”

Then, hit the Enter key.


If you want to skip this, then just type this command,

“Dism /Online /Cleanup-Image /RestoreHealth”.


You can find the details of the SFC scan on the “sfcdetails.txt” file which will appear on the screen.

Fix 7: Reset the System

In Windows 8/8.1/10, the last thing is to perform a reset of the system. Before applying the steps, note down some information:

  • This method will delete all the files from your device. So, you replace them to an external device.
  • If you use Windows 8.1, a reset will turn back your computer to Windows 8. After completing the Reset operation, you should update to Windows 8.1


Now, follow the steps mentioned below:


  1. Restart the computer and press the F8 key or the F11 key.
  2. Now, choose a keyboard layout and select Troubleshoot
  3. Click on Reset your PC.
  4. Follow the instructions to complete the process and check if the issue still appears or not.

Wrapping Up

After applying all the above fixes, you will easily resolve error code 0xC000021a. In case, you face any difficulty or have any doubts in your mind regarding applying any of these solutions, then the best way is to put your feedback in the comment section. Hope this article has been helpful enough for you to get rid of this issue.