Problem booting Windows 2012R2 VM on Windows 2025 Hyper-V

Stefan Cuypers 100

We're having a problem with a Windows Server 2025 Hyper-V cluster.

We have 2 identical clusters (same hardware, same BIOS version) and when we move a Windows 2012R2 VM from one cluster to another it does not boot any more (tested with 2 different VM's).

The error is a blue screen 0x7B (INACCESSIBLE_BOOT_DEVICE).

If we move the machine back to the other cluster it boots just fine.

Only difference I see is the cluster path level. The working cluster is an older Windows Update (KB5058411, KB5058523 and KB5054979).

Whereas the newer cluster has KB5063666, KB5062553, KB5056579 and KB5059502. It tried installing KB5064489 also, but that does not help.

A VM with Windows server 2022 of 2025 does move fine, so it seems to be linked to 2012R2.

I also tried to install a brand new 2012R2 VM from the original iso and then completely upgrading it with Windows Update and that machine is working fine. It seems to have the same verson of storage drivers as the non working VM.

The faulting VM does boot succesfully into recovery mode. I tried bootrec /fixmbr and bootrec /fixboot, but that does not help.

TPIT 1 Reputation point

2025-07-21T03:47:13.84+00:00

Same issue here. Sadly I could not pin down the exact faulty update!

but thanks for your direction!

Thought, I killed my VM. Even the back up…. :D

Answer accepted by question author

Vladimir Shebaldenkov 145

I compared the registry of a VM that boots with one that doesn’t and found some differences.

Then I booted into recovery mode, copied the missing registry keys, and successfully booted the Windows Server 2012 R2 VM on a 2025 Hyper-V host.

reg load HKLM\TempHive c:\Windows\system32\config\SYSTEM

reg copy HKLM\TempHive\ControlSet001\Enum\ACPI\VMBus HKLM\TempHive\ControlSet001\Enum\ACPI\MSFT1000 /s

reg copy HKLM\TempHive\ControlSet001\Enum\ACPI\Hyper_V_Gen_Counter_V1 HKLM\TempHive\ControlSet001\Enum\ACPI\MSFT1002 /s

Bjørn Bendix 10 Reputation points

2025-11-09T10:54:45.4333333+00:00

Works perfect! Thx for your work!
TPIT 1 Reputation point

2025-11-09T12:25:02.85+00:00

Thanks !
Hammer 0 Reputation points

2025-11-09T20:50:35.9533333+00:00

Worker for me too! Thank you!!!
Stefan Cuypers 100 Reputation points

2025-11-10T08:12:41.2766667+00:00

Great work! Works for me too. Thanks a lot.
Andy Bryant 20 Reputation points

2025-11-10T09:51:03.03+00:00

Works for me too. Awesome job! Thank you @Vladimir Shebaldenkov
Richard Hunt 0 Reputation points

2025-11-11T06:31:51.77+00:00

Could you not just export the two keys and then import them in the same HKLM/System/CurrentControlSet/Enum/ACPI root or must be done in recovery mode and in must use ControlSet001 ?
Stefan Cuypers 100 Reputation points

2025-11-11T08:44:48.1+00:00

Some more analysis on what in KB5060842 triggers the problems.

Analysing the ACPI configuration in the BIOS it seems that the ids of some devices have changed.

The 'VMBus' name was defined as an _HID (hardware id).

After the update it is defined as a _CID (compatible id) and MSFT1000 has become the _HID.

Same applies for the Hyper_V_Gen_Counter_V1 device which has become _HID MSFT1002.

Though this should theoretically not pose a problem (Windows should look at both _HID and _CID's) it seems Windows 2012R2 (or older Hyper-V integration services on it) has a problem with this for boot devices.
Glenn Rimington 0 Reputation points

2026-02-09T23:01:29.45+00:00

FANTASTIC!!!! - That worked for me too. Thank you.
Peter Jericho 0 Reputation points

2026-02-09T23:20:11.7033333+00:00

Worked straight away. Thank you.
MARKO TAMM 0 Reputation points

2026-02-26T20:02:00.2866667+00:00

Thank You very much, You saved me alot of time :)
Mulani, Waqas 0 Reputation points

2026-03-01T08:12:38.1733333+00:00

I wanted to let you know that this fix works for me as well.

Thank you so much for all your effort in finding this solution.
CARLOS ANDRES BUITRAGO C 0 Reputation points

2026-03-16T18:15:02.2433333+00:00

Gracias!!
Fernando J. Pineda B 0 Reputation points

2026-08-28T13:40:29.5233333+00:00

I used this procedure on 08-27-2026 to gain access to a Server 2012 VM (Host on Server 2012R2 Crashed and serious damaged and unbootable) imported via Server Backup on a 2025 Server Hyper-V Host.

I found two problems, the first one is protections on the registry zone if the computer you are using to edit the registry have KB5060842 installed or its up to date and recently installed, y manage to use an old VM on Windows 10 24H2 and was able to do it (It shows an access denied error but make the changes on the registry file on the TempHive)

The second problem is that the VM (Now able to boot) will boot just once, so don't restart it or turn it off until you upgrade the OS on the VM (InPlace-Upgrade) or get whatever you need from the VM (Don't restart or shut down)

Probably you will get a VM working but without operational network, in my scenario, it get solved while you run the update to server 2019 or newer OS.

Thanks a lot to Vladimir Shebaldenkov to get us a lead to work and solve the problems!

17 additional answers

Andy Bryant 20 Reputation points

2025-07-24T10:57:09.7266667+00:00

I have exactly the same problem as Stefan. It's all the more frustrating as I can export/import the VM's to 2016 & 2022 Hyper-V hosts and they work flawlessly. Also, if I create a vanilla 2012R2 VM, leave unpatched, go through the export/import cycle that also works. So, it looks like it's something that was introduced in a Windows Update somewhere along the line. Looking on the EFI partition there are some differences there. Ultimately, the 2012R2 VM's will be replaced but I need to get them on to the new cluster first.

I tried adding an additional SCSI controller, but I also didn't have success.
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BryceSor 5,500 Reputation points Volunteer Moderator

2025-07-24T21:16:34.9266667+00:00
Both showing so its down to a patch or KB how it changed the way its interacts with the host.

all start valves should be set at 1

--- Auditing Driver: storvsc ---

Start value: 0

Group: Base

Type: 1

ImagePath: System32\drivers\storvsc.sys

--- Auditing Driver: vmbus ---

Start value: 0

Can you make a copy of the VM just for testing and try the following,

Boot the problematic VM on the older cluster and:

powershell
```
Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Services\storvsc" -Name Start -Value 1
Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Services\vmbus"  -Name Start -Value 1
New-Item -Path "HKLM:\SYSTEM\CurrentControlSet\Services\winhv" -Force | Out-Null
Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Services\winhv" -Name Start -Value 1
```
Then shut down, export, and move to the patched cluster. This forces early driver load on the one running Windows Server 2025, specifically the host that includes the newer update set: KB5063666, KB5062553, KB5056579, KB5059502, and possibly KB5064489
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Stefan Cuypers 100 Reputation points

2025-07-25T06:54:45.46+00:00

I just tried that and first tried to reboot on the older (working) cluster. The VM now blue-screens there with a 0x7B. So this seems to make things worse.

BryceSor 5,500 Reputation points Volunteer Moderator

2025-07-25T09:31:09.0933333+00:00

Very sorry about that Stefan, I have mis-read your original question, have I got this right, you have two clusters on Server 2025 one runs the 2012R2 and the other doesn't,

only difference is how they are updated as far as KBs.

Stefan Cuypers 100 Reputation points

2025-07-25T10:18:11.8666667+00:00

On the newer cluster the problem remains with those registry adjustments.

We indeed have 2 Server 2025 clusters. We had a lot of problems upgrading from Azure HCI to Azure Local on a 4-node stretched cluster.
So we decided to move to 2 clusters and to Windows Server 2025 (to have long term support and not being forced into upgrades too often).
We installed the first 2-node 2025 cluster beginning of June and successfully moved all VM's to it. It was based on the May 2025 release of Windows Server 2025 and then upgraded via Windows Update.
Since that has been succesfull we then reinstalled the other 2 nodes to a Windows 2025 cluster, this time using the June 2025 release of Windows 2025 and fully patched (with obviously more recent patches).
We noticed the problem when redistributing VM's to the newly installed cluster. It worked for Win2022/25 VM's, but not for 2012R2 VM's. Still to test a few Server 2008 servers that are not so easy to get rid of. Maybe they will have the same problem.

Andy Bryant 20 Reputation points

2025-07-25T12:53:43.2966667+00:00

As I have a very similar situation to to Stefan, I thought I'd try an experiment.

I created a new nested 2025 hypervisor on our 2025 cluster. Our Cluster is a 4 node 2025DC set up fully patched as of July 2025. Based on HPE ROK media.

I fired up the nested hypervisor, did not apply any patches and imported the 2012R2 VM. It fired straight up without issues and functions normally! So it does indeed appear to be 2025 update that is causing the issue.

Peter Stam 46 Reputation points

2025-07-25T18:28:38.6+00:00

@BryceSor Doing this will make the 'source' VM not boot anymore, same BSOD inaccessible boot device, no matter is secure boot is on or off.

BryceSor 5,500 Reputation points Volunteer Moderator

2025-07-25T21:46:20.6433333+00:00

iF 2025 May server works with 2012 R2 but the later 2025 server updates puts a spanner in the works, have you tried using DISM to remove the later KB on the server?

Do one at a time and you might find which update is causing your issue.

Starting with these KB5063666, KB5062553, and KB5059502.

Stefan Cuypers 100 Reputation points

2025-07-26T07:02:36.53+00:00

I tried to test this with nested virtualization (thanks @Andy Bryant for the tip).

And here is what I found:

If I install from the Windows 2025 June 2025 DVD the 2012R2 VM does not work.

If I install from the original 2024 Nov 2025 DVD the 2012R2 VM boots just fine.

That confirms without any doubt I think that there is a problem with an update somewhere. I'll try applying patches now on the working 2025 to figure out which patch causes the problem. The May DVD still worked (but I can't download it any more to start from it), so I can start with the May update...

Stefan Cuypers 100 Reputation points

2025-07-26T08:21:48.73+00:00

After applying KB5058411 (May 13) the 2012R2 VM boots succesfully.

After applying KB5060842 (Jun 10) the 2012R2 VM does not boot any more.

So the cause is in KB5060842.

TPIT 1 Reputation point

2025-07-26T08:49:07.6533333+00:00

Thanks for figure this out.

that was the Route I was gooing, but since a bit lack of time I was deinstalling a past updates :)

Stefan Cuypers 100 Reputation points

2025-07-26T09:00:38.49+00:00

I've logged a ticket with Microsoft support on this on Thursday. Still waiting for first reponse though.

Peter Stam 46 Reputation points

2025-07-26T09:57:11.9166667+00:00

VM ISO: SW_DVD9_Windows_Svr_Std_and_DataCtr_2012_R2_64Bit_English_-4_MLF_X19-82891.ISO

Both hosts clean installation no Windows updates

Winver 24H2 (26100.2894)

HOST ISO: SW_DVD9_Win_Server_STD_CORE_2025_24H2.3_64Bit_English_DC_STD_MLF_X23-94773.ISO

VM2012R2 installation with secure boot enabled, template Microsoft Windows -> no boot, the image's hash was denied

VM2012R2 installation with secure boot enabled, template Microsoft UEFI Certificate Authority -> no boot, the image's hash was denied

VM2012R2 installation with secure boot disabled -> boots

Winver 24H2 (26100.1742)

HOST ISO: SW_DVD9_Win_Server_STD_CORE_2025_24H2_64Bit_English_DC_STD_MLF_X23-81891.ISO

VM2012R2 installation with secure boot enabled, template Microsoft Windows -> no boot, the image's hash was denied

VM2012R2 installation with secure boot enabled, template Microsoft UEFI Certificate Authority -> no boot, the image's hash was denied

VM2012R2 installation with secure boot disabled -> boots

@Stefan Cuypers what is the .iso name u used for the working version?

We logged a ticket last week but the response was we had no ESU, so no support anymore...

We ran into this problem when live migrating 2012R2 server from a 2022 host cluster to a new installed 2025 host cluster. The live migration works and the VM keeps running but cannot reboot. Than we get the inaccessible boot device BSOD.

Stefan Cuypers 100 Reputation points

2025-07-26T10:03:33.5333333+00:00

Hi Peter, I've noticed too that you need to install the 2012R2 without Secure Boot. Seems the certificates used on the 2012R2 DVD are not present any more in Windows Server 2025 host.

However if you fully update the 2012R2 via Microsoft Update you can enable secure boot and it will work.

Peter Stam 46 Reputation points

2025-07-26T10:05:29.84+00:00

I tried that fully update the 2012R2 but it's not working, can u maybe post the storsvc.sys driver version of the working 2012R2 VM running on a hyper-v 2025 host?

Peter Stam 46 Reputation points

2025-07-26T10:06:17.8766667+00:00

I tried that fully update the 2012R2 but it's not working, can u maybe post the storsvc.sys driver version of the working 2012R2 VM running on a hyper-v 2025 host?

Stefan Cuypers 100 Reputation points

2025-07-26T10:14:22.51+00:00

I have installed a working 2012R2 VM as follows:

Create a new VM, Gen2, disable secure boot

Mount the ISO SW_DVD9_Windows_Svr_Std_and_DataCtr_2012_R2_64Bit_English_-4_MLF_X19-82891 (downloaded it from volume licensing in O365)

Installed the VM from the ISO

Once installed apply all Windows updates (did this in several steps since there are a lot)

After the last updates are applied, enable secure boot again

That gave me a new working 2012R2.

The storsvc.sys after all the updates is version 6.3.9600.19984 dating 3/4/2021 0:02

Stefan Cuypers 100 Reputation points

2025-07-26T10:19:03.6466667+00:00

Here are some notes I took while Windows Updating the image:

KB5052108 (Servicing Stack Update)

(109) KB4054519 - OK

(103) KB5031419 - 2023-10 Security Monthly Rollup - OK - Secure boot works now

(95) KB4486105 - .Net 4.8 - OK

(83) KB3185319 IE 11 - OK

(82) All Security Updates (also .net) - OK (.net one failed though)

(61) .Net Security Update

(60) -> first 10 Update for Windows Server 2012 R2 - ok

(50) -> next 10 Update for Windows Server 2012 R2 - ok - check for updates

Then continued per 10 updates until all are installed.

Peter Stam 46 Reputation points

2025-07-26T10:20:13.1033333+00:00

thank you Stefan, same version here but not booting at all...have to dig deeper I guess :)

Dimitri Iacomi 0 Reputation points

2025-07-26T13:57:08.3233333+00:00

I have exactly the same problem. A working 2012 R2 vm imported on a new 2025 host cannot boot anymore. BSOD regardless of secure boot on or off, I'm out of ideas...

Peter Stam 46 Reputation points

2025-07-26T20:21:37.9133333+00:00

Host clean installation 2022 so we can boot a server to be migrated from the old Hyper-V cluster, no Windows Updates

SW_DVD9_Win_Server_STD_CORE_2022_2108.16_64Bit_English_DC_STD_MLF_X23-32717.ISO

Moved the original 2012R2VM (not changed, no Windows Updates to latest with SSU) to 2022 host, secure boot on, -> boot

Moved the VM from 2022 host to 2025 host, secure boot on, -> boot (???)

Updated the 2025 host (24H2.3) with all the Windows Updates

Security Intelligence Update for Microsoft Defender Antivirus - KB2267602 (Version 1.433.88.0) - Current Channel (Broad)

2025-07 Cumulative Update for .NET Framework 3.5 and 4.8.1 for Microsoft server operating system version 24H2 for x64 (KB5056579)

2025-07 Cumulative Update for Microsoft server operating system version 24H2 for x64-based Systems (KB5062553)

Windows Malicious Software Removal Tool x64 - v5.134 (KB890830)

Update for Windows Security platform - KB5007651 (Version 10.0.27840.1000)

Secure boot off, -> no boot (!)

Secure boot on, -> no boot (!)

Removed

2025-07 Cumulative Update for Microsoft server operating system version 24H2 for x64-based Systems (KB5062553)

Secure boot off, -> boot (!)

Secure boot on, -> boot (!)

Installed again

2025-07 Cumulative Update for Microsoft server operating system version 24H2 for x64-based Systems (KB5062553)

Secure boot off, -> no boot (!)

Secure boot on, -> no boot (!)

So for me the problem is clearly with KB5062553

Andy Bryant 20 Reputation points

2025-07-27T08:24:50.3733333+00:00

Having done my own testing. I agree with Stefan, the problem was first introduced with KB5060842 in June. The subsequent KB5062553 would also contain the problem, but it started with KB5060842.

Thank for raising a ticket with Microsoft @Stefan Kuypers

Peter Stam 46 Reputation points

2025-07-27T09:04:17.13+00:00

@Andy Bryant u are right, problem is with KB5060842 also, just tested.

Ben Gillam 10 Reputation points

2025-07-30T09:38:28.18+00:00

This method killed the server on original 2012 host for me.

had to boot with last known good config to boot again

It also didnt work on the new server either
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Peter Sommer 10 Reputation points

2025-07-25T13:26:43.41+00:00
I have a customer with the exact same issue. Windows Server 2025 S2D Cluster. After applying the last Updates, a Restart of the running Win 2012R2 VMs will boot into recovery. Things i already testet:
- New VM Gen1 and Gen2 with the 2012R2 vhdx -> not working
- disable secure boot -> not working
- disable integration services -> not working
- booting in safe mode -> not working
VM ist configversion 12

On another Server 2025 S2D cluster with older updates, the same VM is booting
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Andy Bryant 20 Reputation points

2025-07-25T13:31:27.0066667+00:00

We need to identify which CU caused the problem now. I'll try that on my freshly built nested hypervisor.
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Kalabis Tomáš 15 Reputation points

2025-07-29T12:30:02.08+00:00

hi guys, the customer had a same problem:

Failover Cluster 2025 with 3 identical nodes, we uninstall the (KB5060842) from the one node and reboot it, after we migrate the affected VM (WS2012R2) back to the node and VM boot succesfully.

post about this issue on my blog:
https://tomaskalabis.com/wordpress/problem-booting-windows-2012r2-vm-on-windows-2025-hyper-v/
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Problem booting Windows 2012R2 VM on Windows 2025 Hyper-V

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