Review: Fix for Hyper-V Host Startup Problem in Windows (January 2022)

Windows[Geman]The January 11, 2022 security updates for Windows Server 2012/R2 resulted in the Hyper-V host subsequently failing to start. As of January 17, 2022, Microsoft then released special updates to correct this issue. Here is a follow-up on this issue.


The Hyper-V host startup issue

Shortly after the release of the January 11, 2022 security updates for Windows Server 2012 and Windows Server 2012 R2, administrators here on the blog came forward reporting Hyper-V hosts failing to start. There was the following from user TomTom in this German comment:

VM's on Server 2012 R2 hypervisor no longer start.
The error message is that the hypervisor is not running.

In the event log it is logged when starting the HyperV server: (ID 80, Hyper-V hypervisor)
Hypervisor launch failed; The operating systems boot loader failed with error 0xC00000BB.

I had addressed the issue in a timely manner in the blog post Windows Server 2012/R2: January 2022 Update KB5009586 bricks Hyper-V Host. The following security updates from January 11, 2022 were responsible for this error:

  • KB5009624: Windows Server 2012 R2 (Monthly Rollup)
  • KB5009624: Windows Server 2012 R2 (Security only)
  • KB5009586: Windows Server 2012 (Monthly Rollup)
  • KB5009619: Windows Server 2012 (Security only)

Microsoft confirmed the issue a few days later in the list of known issues in the support posts linked above, writing:

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

The above explanation also explains why not all Hyper-V installations were affected. Not detailed was the explanation in this comment: Root cause is with code incorrectly referencing the file type for the hvloader Win2k12 R2 servers running on UEFI platform will see this regression while BIOS machines will not see this regression. The only remedy was to uninstall the security updates in question. After that the hypervisors started normally again.

Out-of-band updates released

Then, as of Jan. 17, 2022, Microsoft has released special updates that it says are intended to correct bugs relevant to that version of Windows. Here is the list of updates that are supposed to correct the Hyper-V bug:


In the status area of Windows Server 2012 / R2, the entry Virtual machines (VMs) in Hyper-V might fail to start can be found at the same time, indicating that the Hyper-V startup problem in Windows 8.1, Windows Server 2012 R2 and Windows Server 2012 should be fixed by the above correction updates.

It should be noted that only one fix update was released for the respective server version – notwithstanding the fact that a monthly rollup and a security only update were released for each as of 11/1. Since the fix updates for Windows Server 2012 / R2 are not cumulative, the old updates from 11.1. and the update from 17.1. are required for installation (see also this discussion).

For those concerned about a domain controller running into the boot loop on the Windows Server 2012 R2 machine in question, you can install the Jan. 11 security update and then the Jan. 17 fix update without rebooting the machine in each case. Then the Hyper-V bug should be fixed without the DC boot loop occurring.

One thing to note is that the updates can be downloaded and installed via the Microsoft Update Catalog or imported into WSUS for distribution from the download. After installing the updates, the Hyper-V instances should start up again. I have not heard of any problems from the blog readership.

Similar articles:
Windows Server: Out-of-Band Update fixes Remote Desktop issues (2022/01/04)
Microsoft Office Updates (January 4, 2022)
Microsoft Security Update Summary (January 11, 2022)
Patchday: Windows 8.1/Server 2012 R2 Updates (January 11, 2022), boot loop reported
Patchday: Windows 10 Updates (January 11, 2022)
Patchday: Windows 11 Updates (January 11, 2022)
Patchday: Updates for Windows 7/Server 2008 R2 (January 11, 2022)

Windows Server: January 2022 security updates are causing DC boot loop
Windows VPN connections (L2TP over IPSEC) broken after January 2022 update
Windows Server 2012/R2: January 2022 Update KB5009586 bricks Hyper-V Host
Microsoft patch day issues Jan. 2022: bugs confirmed, but updates not pulled

Microsoft Microsoft Januar 2022 Patchday Revisions (2022/01/14)
Windows Out-of-band Updates fixes Jan. 2022 patch day issues (Jan. 17, 2022)
Windows 10/Server: Out-of-band Updates fixes Jan. 2022 patch day issues (Jan. 17, 2022)
Out-of-band Updates for Windows Server 2019 fixes Jan. 2022 Patch day issues (Jan. 18, 2022)
Windows 7/8.1; Server 2008R2/2012R2: Out-of-band Updates with Fixes for Jan. 2022 Patch day Issues (2022/01/17)

Review: Fix for Windows IPSec VPN Connection Issues
Out-of-Band Updates for Windows (Jan. 17/18, 2022) doesn't fixes ReFS Issues complete

Cookies helps to fund this blog: Cookie settings

This entry was posted in Update, Virtualization, Windows and tagged , , , , . Bookmark the permalink.

3 Responses to Review: Fix for Hyper-V Host Startup Problem in Windows (January 2022)

  1. James Parker says:

    I've juggled back and forth with different machines and admittingly ended up using VirtualBox for hosting my virtual machines (it seemed to be the easiest, although it did have the least options compared to other virtual machine programs). For anybody trying to host a website using a virtual machine, I will probably say don't also (this is a thing I've heard people doing). I'll be honest, regarding hosting sites on virtual machines, I've meddled around with Windows virtual machines for a while with little luck (besides of course being slow [I did find Linux Ubuntu Server to be fast, however]). When it comes to hosting websites, I would host them with a hosting provider. I do admittingly use virtual machines daily though, and they're particularly useful when you need to juggle between multiple operating systems to perform certain duties and tasks. I currently have Windows 10 Pro (64-bit) and Ubuntu (64-bit) installed in a separate virtual machine because they're both uniquely great at performing different tasks. Virtual machines are useful depending on your specific task I suppose.

    • guenni says:

      I've removed the SEO link to your hosting service, due it's against the policy of my blogs. Thanks.

  2. Paul says:

    I was able to fix this. Firstly when you turn off Intel (VMX) Virtualisation Technology in the BIOS, the machine boots, but hyper V doesn't work, you can at least use that to get into windows if you need it. For the actual fix I found that if I switch the "Efficient cores" BIOS setting down to zero – then you can turn VMX back on and the machine will boot with HyperV enabled

Leave a Reply

Your email address will not be published. Required fields are marked *