Since then, there has been a constant stream of complaints that printing is causing Windows 10 to crash with an "APC_INDEX_MISMATCH for win32kfull.sys" blue screen of death crash.
According to posts by system administrators on Reddit [1, 2], the Windows 10 crashes began immediately after installing yesterday's KB5000802 and KB5000808 updates and attempting to print.
"Hey Jen, several folks over in r/sysadmin, myself included, are seeing a BSOD post-update (on at least Win10 20H2 so far) when sending print jobs to any Windows Server printer share using a type 3 Kyocera KX driver. (i.e., type 4 KX driver and other generic type 3/4 drivers don't exhibit the issue)," one Reddit user posted.
"KB5000802 broke all Kyocera printing at one of my clients. BSOD's in the same style as the problem with printing back in June 2020," confirmed another user, while stating that none of the normal fixes appear to be working.
Some of the printer brands known to be affected, include Kyocera, Ricoh, and Dymo.
Using virtual machines that received these updates yesterday, BleepingComputer has rolled back to the March preview updates and is no longer offered the KB5000802 cumulative update like we were yesterday.
This indicates that Microsoft has pulled the updates from Windows Update while they look into the issues. However, the updates are still available via the Microsoft Update Catalog.
Furthermore, some of our machines are being offered the KB4601382 Preview cumulative update released on February 24th, but not yesterday's KB5000802 update, indicating that a security update is likely causing the crashes.
Yesterday, Microsoft released two security updates, tracked as CVE-2021-1640 and CVE-2021-26878, to fix a privilege elevation vulnerability in the Windows Print Spooler.
Microsoft does not include security updates in the Preview cumulative update offered last month, which is likely why users did not experience the same crashes when printing.
How to fix the win32kfull.sys crashes when printing
Unfortunately, attempts to fix the issue by upgrading printer drivers have been mainly unsuccessful.
Instead, Windows 10 users have been forced to uninstall the KB5000802 or KB5000808 updates for printing to work correctly again.
If you are affected by the printing bug, you can uninstall the Windows 10 KB5000802 cumulative update by closing applications and opening a command prompt. In the command prompt, enter the following command:
wusa /uninstall /kb:5000802
To uninstall the Windows 10 KB5000808 cumulative update, use this command instead: