A Microsoft Windows Update is wreaking havoc with printers worldwide this week—KB50000802 (for newer Windows 10 builds; older Windows 10 and Server builds may have a KB ending in 808 or 822 instead) was intended to provide updates to security "when Windows performs basic operations," but the update crashes some print drivers due to overflowing a GDI Object limit of 10,000.
The bug afflicts a wide range of printers and print drivers, as reported by WindowsLatest earlier this week. We can confirm having seen the issue on a Windows 10 2004 PC, which crashes with APC_INDEX_MISMATCH (photo above) after printing to any of several models of Kyocera printer (some local, some network).
If you're afflicted with this bug yourself, you can get some relief by uninstalling KB50000802 until Microsoft comes out with a fixed update, presumably by April's Patch Tuesday.
On a Windows 10 or Windows Server PC version 2004/20H2, click Start --> type "Control Panel" and hit enter --> go to Programs, then Programs and Features. From there, click "View installed updates" on the left-hand pane and uninstall Security Update for Microsoft Windows KB50000802).
For Windows PCs version 1909, the same fix (and problem) is in KB50000808. If you're on version 1809, look for KB50000822. For more technical detail, Belgian tech site winking.be has an excellent overview.
This flaw may also affect Windows 8.1 or Windows 7 PCs with KBs 848, 853, 841, or 851... but if you're still on Windows 8 or Windows 7 at this point, you've got worse problems than this. Please upgrade!