How to fix 0xC000021A error on Windows

Error 0xC000021A is a dead blue screen error that occurs when the Windows user-mode subsystem is compromised. Windows subsystems are WinLogon or Client Server-Run Time Subsystem (CSRSS). These two subsystems are mandatory components for Windows to work. If this system is compromised, Windows will stop running and show this error. This article will guide you to fix 0xC000021A error on Windows versions.

Error 0xC000021A is also known as:

1. STOP 0xC000021A
2. STATUS_SYSTEM_PROCESS_TERMINATED (Status System Process Terminated)
3. HALT: c000021a {Fatal System Error}
4. STOP c000021a

Below is the error message 0xC000021A on Windows XP, Windows Vista or Windows 7 systems.

How to fix 0xC000021A error on Windows Picture 1

In Windows 8, 8.1 or Windows 10, an error message will appear as shown below.

How to fix 0xC000021A error on Windows Picture 2

The cause of error 0xC000021A

1. The software or driver is not properly configured

The main cause of this error is a corrupted software or system driver.

2. The system registry is corrupted

Another cause of this error is a corrupted system registry. This is caused by a write / read error, power failure or virus attack.

How to fix 0xC000021A error on Windows

How to fix 0xC000021A error on Windows XP

1. Boot into Last Known Good Configuration mode

When Windows XP boots into Last Known Good Configuration mode, forcing the computer to use the previously saved Windows Registry version. This version is saved when the computer successfully boots without an error.

To boot the computer into the Last Known Good Configuration mode, follow these steps:

Step 1 . Restart the computer.

Step 2. Wait for the computer to complete the POST process (system information appears on the screen).

Step 3. Quickly press the F8 key repeatedly until you see the boot options list.

Step 4. Select Last Known Good Configuration .

Step 5 . Press Enter .

Step 6 . Wait for the computer to boot into this mode.

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2. Uninstall the previously installed software or driver

If this error occurs after installing new software or hardware drivers, boot into Safe Mode and uninstall it. Contact the manufacturer or check the updated version of the software or driver that is compatible with Windows XP.

To enter Safe Mode on Windows XP, refer to the article Getting Safe Mode on Windows XP.

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3. Run system restore

If System Restore is enabled on your computer, you can restore the system to a restore point before an error occurs. To run System Restore in Safe Mode on Windows XP, follow these steps

Step 1 . Restart the computer.

Step 2 . Press F8 to boot into Windows Advanced Options menu.

Step 3 . Using arrow keys, select Safe mode with Command Prompt .

Step 4 . Press the Enter key.

Step 5 . Login to Command Prompt as admin.

Step 6 . On the Command Prompt that appears, type the following command and press Enter :

 % systemroot% system32restorerstrui.exe 

Step 7. Follow the on-screen instructions to restore the system to the previous point.

How to fix 0xC000021A error on Windows Picture 5

4. Use Dr.Watson software

Although 0xC000021A error is usually caused by software or incompatible drivers you recently installed, but you can debug with Dr. Watson in Windows XP to fix other problems, follow these steps:

Step 1. Open Command Prompt.

Step 2. Type the following command and press Enter after each command.

 System RootSystem32Drwtsn32.exe -I 

 System RootSystem32Drwtsn32.exe 

Step 3. Then choose from the following options: Append to existing log file, Create crash dump, Visual Notification . By default, Dr. Watson will create a log file in the following path:

 C:Documents and SettingsAll Users.WINNTApplication DataMicrosoftDr Watson 

If no log file is created, you can use the Userdump.exe utility.

Step 1. Download User Mode Process Dumper 8.1 according to the link below:

  http://www.microsoft.com/en-us/download/details.aspx?id=4060 

Step 2. Run Setup.exe.

Step 3. Access Control Panel.

Step 4. Click Process Dump .

Step 5 . On the Exception Monitoring tab, click New . After adding the program name (Lsass.exe, Winlogon.exe, Mtx.exe, Dllhost.exe) to the Monitor list, click OK .

Step 6 . At Monitor, click on the name you just added and click on Rules .

Step 7 . Click on Custom Rules and select the type of error you want to fix.

5. Other measures

If the above methods do not fix the problem, try the following:

1. Reinstall Windows XP using the original installation disc.
2. Install all Service Pack packages for Windows XP.

How to fix 0xC000021A error on Windows Vista and Windows 7

1. Uninstall the previously installed software or driver

If you have just installed the software or driver on the system, boot into Safe Mode and uninstall it. On Windows Vista, restart the computer and press the F8 key before the Windows Vista logo appears. In the Advanced Boot Options menu, select Safe Mode and press Enter .

On Windows 7, access Safe mode by looking at the instructions in the article Activating Safe Mode in Windows 7.

2. Use Startup Repair

The original installation disc of Windows Vista or Windows 7 has the Startup Repair tool that can fix 0xC000021A. Follow the steps in the article How to use the Startup Repair tool to troubleshoot problems in Windows 7. On Windows Vista, do the same thing as on Windows 7.

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3. Boot into Last Known Good Configuration mode

Similar to Windows XP, you can boot into the Last Known Good Configuration mode to use an error-free version of the System Registry.

To boot into this mode on Windows Vista or Windows 7, follow these steps:

Step 1 . Restart the computer or turn it off completely and then press the power button to start it.

Step 2. Before the Windows Vista or Windows 7 logo appears on the screen, press the F8 key repeatedly. On certain laptop versions, you need to press the Fn key along with the F8 key.

Step 3. When the system boots into the Advanced Boot Options menu, select L ast Known Good Configuration (Advanced) from the list using the arrow keys.

Step 4 . Press Enter .

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4. Use System Restore

If System Restore is enabled on your computer, you can select a restore point before an error occurs to boot into the system. If the 0xC000021A error occurs due to incompatible software or drivers, System Restore will restore the computer to the point before the software or driver is installed on the system.

To use System Restore, refer to the article How to use System Restore on Windows.

5. Use the dism command

If System Restore fails to load, you can run dism to automatically restore the last restore point using the Command Prompt (System Restore is required to use this method).

Step 1. Restart the computer and press F8 to boot into Windows Advanced Options .

Step 2 . Select Repair your computer and press Enter . If there is no Repair option, use the original installation disk to boot into the System Recovery Options .

Step 3. When in the System Recovery Options menu, select Command Prompt .

Step 4 . On the Command Prompt, type the following command and press Enter .

 dism / image: C: / cleanup-image / revertpendingactions 

Replace C: with the Windows Vista or Windows 7 installation drive letter.

6. Disable service in System Configuration

If error 0xC000021A is caused by software or driver when booting into Windows Vista or Windows 7, you can disable the services in the System Configuration utility (msconfig).

Step 1. Boot into the system

Step 2 . Click on Start .

Step 3 . Type msconfig and press Enter .

Step 4. Access the Startup (or Services ) and disable all the listed services, then click OK.

Step 5. Click Restart to apply changes.

Step 6 . Restart the computer.

How to fix 0xC000021A error on Windows Picture 8

If the computer works after disabling the service, the problem is caused by one of the services in the Startup tab. To determine the service that caused the error, reactivate each service one by one and restart the computer until a problematic service is identified.

How to fix 0xC000021A error on Windows 8.8.1 and 10

1. Clean Clean implementation

To perform Clean Boot, refer to the article How to perform Clean Boot on Windows 10/8 / 7. If the computer no longer displays error 0xC000021A, one of the services in the Startup tab causes problems. To determine the service that caused the error, return to msconfig and activate each service, restart the computer until the problem is identified.

2. Uninstall software and drivers

Similarly, the new software and drivers installed may cause an error. If way 1 works, you need to uninstall the software or driver. If you cannot boot into the system, try booting into Safe Mode and uninstalling the software or driver. Refer to the article Activating, using and disabling Safe Mode in Windows 8 and How to access Safe Mode Windows 10 on startup.

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3. Run dism command

Start the system into Safe Mode with Command Prompt , run the dism command by following these steps:

Step 1. Reboot the system.

Step 2. Press F8 key, before the Windows logo appears. If the F8 key does not work, try Shift and F8 or press F11 .

Step 3. Select Troubleshoot> Advanced Options> Startup Settings

Step 4. Click Restart.

Step 5 . Press F6 to boot into Safe Mode with Command Prompt .

On the Command Prompt, type the following command and press Enter:

 dism / image: C: / cleanup-image / revertpendingactions 

Replace C: with the drive letter to install Windows 8 / 8.1 or Windows 10. You can run additional commands

 cd C: WindowsWinSxS 

And then run the command:

 move pending.xml pending.old 

4. Restore the system

If System Restore is enabled on your computer, you can use it to restore your computer to a point before an error occurs. Refer to the article on way 4 of the section How to fix 0xC000021A error on Windows XP and Windows 7.

5. Disable driver signatures

If you disable Driver Signature, Windows 8 and Windows 10 will use drivers that are not signed directly by Microsoft. This way can fix 0xC000021A error caused by one of the load drivers during boot.

1. How to install the driver has not been Signed on Windows 10

Step 1. Restart the computer.

Step 2 . Press F8 or F11 key.

Step 3. Select Troubleshoot> Advanced Options> Startup Settings, then click Restart.

Step 4 . Press F7 to boot into Windows with the driver disabled the signature.

5. Reset the system

On Windows 8 and Windows 10, you can perform a system reset. However, before doing so, you should note that this operation will delete all personal files on your computer. And If your system uses Windows 8.1, reinstall the system will return to Windows 8. After the reinstallation is complete, you need to update to Windows 8.1.

Step 1. Restart the computer.

Step 2. Press the F8 or F11 key.

Step 3. Select the key if notified.

Step 4. Click Troubleshoot> Reset your PC . Then follow the instructions on the screen.

1. How to use the Reset feature on Windows 10

I wish you all success!