Microsoft is investigating a known issue resulting in Blue Screen of Death (BSOD) crashes with 0xc000021a errors after installing Windows 10 cumulative update KB5021233 released on Patch Tuesday this month.

The company warned over the weekend that “after installing KB5021233, some Windows devices may boot to an error (0xc000021a) with a blue screen.”

This known issue is likely caused by a mismatch between the file versions of hidparse.sys in system32 and system32/drivers in the Windows folder, “which may cause signature validation to fail during cleanup.”

The list of affected platforms only includes client versions of Windows 10, from Windows 10 20H2 to the latest version, Windows 10 22H2.

Redmond added that it is already working on a patch to address this newly acknowledged issue, but has not yet shared when it will be available.

Workaround for affected Windows 10 systems

However, the company has shared a temporary fix to work around the blue screen issue and reboot the affected systems to boot as expected.

This forces users to copy the hidparse.sys file from the system32 folder to system32\drivers via Windows Recovery Environment (WinRE) so that signature validation no longer fails during cleanup.

To mitigate this issue on affected devices, you should follow these steps:

1. You will need to enter the Windows Recovery Environment. If your device did not automatically boot into WinRE, please see Entry Points in WinRE.
2. Select the Troubleshoot button.
3. Select the “Start recovery, troubleshooting, and diagnostic tools” button.
4. Select the “Advanced Options” button.
5. Select the “Command Prompt” button and wait for your device to restart, if necessary.
6. Your device should reboot into a command prompt window. You may need to log into your device with your password before accessing the command prompt window.
7. Run the following command (Important: if Windows is not installed on C:\windows, you will need to modify the command in your environment): xcopy C:\windows\system32\drivers\hidparse.sys C:\windows\\system32 \hidparse.sys
8. Once the previous command is finished, type: exit
9. Select the “Continue” button.
10. Windows should now start as expected.

“It is not recommended to follow any workaround other than those recommended above. We do not recommend deleting hidparse.sys from your Windows\System32 folder,” Microsoft added.

Redmond is also investigate a known issue Related to this month’s Windows Server Patch Tuesday updates that trigger errors when creating new VMs on some Hyper-V hosts.