Score:1

Hyper-V stopped working after January 2022's Patch Tuesday (2022-01-11): The operating systems boot loader failed with error 0xC00000BB

cn flag
Dai
  • I only just noticed this now, but apparently since 2022-01-11 ("Patch Tuesday" in January 2022) my home network's dev-server's Hyper-V hypervisor has been unable to start.

    • The box is a 6 year-old Xeon E3 machine (UEFI of course), running Windows Server 2012 R2 with the Domain Controller and Hyper-V host roles installed.
  • The Hyper-V Event Logs are littered with errors, but those are all second-order consequences of the initial service failure which is reported with this event in the System event log:

    Level: Error
    Source: Hyper-V-Hypervisor
    Event ID: 80

    Hypervisor launch failed; The operating systems boot loader failed with error 0xC00000BB.

    • The raw XML of the Event says that the 0xC00000BB code is an NTSTATUS error code, which apparently means "STATUS_NOT_SUPPORTED" - which doesn't make any sense as Hyper-V was working fine before Patch Tuesday and I'm not aware of Intel pushing-out any processor microcode updates to disable hardware virtualization like some kind of horrible SPECTRE/MELTDOWN-esque mitigation...
  • As it happened right after patch Tuesday, I'm guessing Microsoft botched a Hyper-V patch - and I probably shouldn't be expecting the best quality-control for security patches for 8.5-year-old OS releases...

  • Any ideas?

Score:3
cn flag
Dai

After a bit more Google-fu, I found this thread on HP Enterprise's public forum and a reply from user MDavidRichard attributes the failure to Microsoft update KB5009586:

No it's nothing to do with HPE. Just remove the Microsoft update KB5009586 and reboot...

Good luck!

Microsoft's page for KB5009586 is now updated with a Known Issue that describes my issue (though without any googleable error-codes, no wonder I didn't find this page earlier):

After installing this update on a device by using Unified Extensible Firmware Interface (UEFI), virtual machines (VMs) in Hyper-V might not start.

This issue is resolved in KB5010797.

However I don't see KB5010797 in Windows Update's available downloads list...

UPDATE: Ah, derp, the KB5010797 patch is for Windows Server 2012 (not Server 2012 R2) while KB5010794 is for Windows Server 2012 R2.

TL;DR:

Install KB5010797 or KB5010794 depending on your OS.

mangohost

Post an answer

Most people don’t grasp that asking a lot of questions unlocks learning and improves interpersonal bonding. In Alison’s studies, for example, though people could accurately recall how many questions had been asked in their conversations, they didn’t intuit the link between questions and liking. Across four studies, in which participants were engaged in conversations themselves or read transcripts of others’ conversations, people tended not to realize that question asking would influence—or had influenced—the level of amity between the conversationalists.