October Windows Update Renders VMWare 2012 R2 Server Unbootable

Windows 2012 R2 Server was unbootable after applying October 2021 Windows Updates.

1. Go into Edit Settings on VM and switch the Windows boot disk to SCSI Controller 0 (it was on 1 which was the paravirtual.)  
2. Force VM to boot into EFI Boot – verify it sees the disk now
3. Try to reboot normally – no go same error
4. Boot to CD ROM ISO for Win2012 R2
5. Go to Repair System, Troubleshooting, Command prompt
6. Run Diskpart
7. List vol
8. Select the FAT32 UEFI Hidden Volume – volume 2 in this case
9. In diskpart assign a drive letter to the UEFI hidden partition “assign letter k:”
10. Exit diskpart
11. cd /d K:\efi\microsoft\boot\
12. bootrec /FixBoot
13. ren BCD BCD.old
14. bcdboot c:\Windows /l en-us /s K: /f All
15. Reboot
16. New boot error

I tried booting into Advanced options and disabling driver signature verification but the server still wouldn’t boot. Searched on this new symptom and finally found a thread that lead to the fix. It turned out to be an unsigned SCSI Paravirtual driver pushed by Windows Update. Kudos to u/oddie121!

Server 2012 R2 on ESXI 7.0 non-accessible boot device from Windows paravirtual SCSI patch
byu/oddie121 insysadmin