Windows 10’s March 2021 cumulative updates are causing serious problems for some people and it’s still not clear how widespread the issue is. The problem was first reported by users of both Windows 10 consumer edition and Windows Server when their devices crashed abruptly with the “APC_INDEX_MISMATCH” stop error code.

In addition to blue screens, users reported that their printers are failing to fully print the documents, apparently due to some kind of compatibility issue in the March cumulative updates – although exactly why this problem is experienced wasn’t clear until today.

A Microsoft spokesperson has now confirmed that the company is aware of the Blue Screen of Death issues caused by the following cumulative updates:

  • KB5000802 (version 2004/20H2)
  • KB5000803 (Windows Server)
  • KB5000808 (version 1909)
  • KB5000809 (version 1809)
  • KB5000822 (version 1803).

In these cumulative updates, there is a worrying “APC_INDEX_MISMATCH” and “win32kfull.sys” Blue Screen of Death bug.

Microsoft noted that the bug is hitting devices with Type 3 printer drivers only. It does not affect printer drivers that are Type 4. Before applying the cumulative updates, Microsoft recommends verifying the type of your printer driver:

  1. Open Windows Search.
  2. Type printmanagement.msc.
  3. In the Print Management window, expand Print Servers.
  4. Click on “computer’s name”.
  5. Select Printers to see the Driver Type for installed drivers.

Before following the above steps, you must have the “Print Management Console” enabled in Windows 10. To enable the console, search for ‘manage optional features’ in Windows Search. On the optional features screen, click on ‘Add a feature’ and enable Print Management Console.

If you see Type 3 printer drivers in the Print Management Console, you should either skip the update or stay prepared for the Blue Screens.

Workaround for APC_INDEX_MISMATCH stop error

If you’re already using the latest cumulative update and you have got the blue screen problem, Microsoft recommends following these steps:

  1. Open Command Prompt (elevated)
  2. Run the following command after replacing “KX driver for Universal printing” with the name of your printer:
    rundll32 printui.dll,PrintUIEntry /Xg /n “KX driver for Universal printing”
  3. The above command will open the printer user interface dialogue box. In the attribute field, if it does not say ‘direct’, run the following command to enable direct printing manually:
    rundll32 printui.dll,PrintUIEntry /Xs /n "KX driver for Universal printing" attributes +direct
  4. Close the printing interface and Command Prompt.

Microsoft also confirmed that it’s working on another update and a solution will be available in the coming week.

Hotfix for APC_INDEX_MISMATCH win32kfull.sys BSOD

Microsoft has kept its word and is now releasing cumulative updates to address the issue, but not for all versions. Only affected and supported versions – Windows 10 version 20H2, version 2004, version 1909, version 1809, and version 1803 – can get the emergency update.

As we mentioned at the outset, after users deployed the March 2021 updates, some discovered that they can no longer print using devices from multiple manufacturers, including Ricoh and Kyocera.

The issue even resulted in Blue Screen of Death errors when using software-based printers or apps with print dialog, such as LibreOffice, Notepad and Microsoft’s own Office suite.

Thankfully, Microsoft has now published the optional cumulative updates to address the issue. If you’re running one of the supported Windows versions that have blue screens after recent patches, you can grab the hotfix by following these simple steps:

  1. Open Settings and head to the Windows Update page.
  2. Check for updates.
  3. Click on the ‘Download and install’ option under the quality updates section.

If you don’t want to apply the hotfix, you could just uninstall the March updates that are causing the issue or wait until the second week of April when the Redmond giant will issue Patch Tuesday updates with the same fix.

About The Author

Mayank Parmar

Mayank Parmar is Windows Latest's owner, Editor-in-Chief and entrepreneur. Mayank has been in tech journalism for over seven years and has written on various topics, but he is mostly known for his well-researched work on Microsoft's Windows. His articles and research works have been referred to by CNN, Business Insiders, Forbes, Fortune, CBS Interactive, Microsoft and many others over the years.