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Windows 8.1/Server 2012 R2 running as a Hyper-V VM on Windows 11 24H2 Host - Secure boot problem

Anonymous
2024-11-14T13:21:42+00:00

I have a problem on Windows 11 24H2 with my Hyper-V host. When I install a fresh copy of Windows 8.1, I cannot turn Secure Boot on and be able to boot the VM, it can have secure boot on when I install from the ISO image, but once it's installed to the virtual hard drive, I have to disable secure boot or else I can't boot, TPM does not seem to matter either way.

Edit:

This problem also is happening in Server 2012 R2

I did some testing with Windows 10. I found that If I install Windows 10 first in a VM, then fresh install Windows 8.1 on top of it, I can enable secure boot. I tried both Windows 10 1507, and Windows 11 24H2, both work. I'm wondering if the boot loaders of windows 2012 R2 and Windows 8.1 are now blocked by the uefi firmware used by hyper-v.

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  1. Anonymous
    2024-11-21T04:34:39+00:00

    You just can't enable secure boot with fresh installed windows 8.1 or server 2012 R2 anymore, it says the image's hash is denied in the hyper-v uefi screen instead of booting, if you turn secure boot off you can boot. I've gone back and tested Windows 11 23H2 as a Hyper-V host, and it has the previous behavior where Secure Boot will work in Server 2012 R2 or Windows 8.1. There are a lot of changes with hyper-v host running on Windows 11 24H2 and also Server 2025 of course. The firmware portions of both legacy and uefi have hardened security and there are some major changes to explore. For example mouse cursor is inverted in most windows before Windows 7 before you have guest additions installed in Hyper-V starting in 24H2. Also network issues in XP virtual machines (I have another post on that topic) It kind of makes sense since those OS are no longer supported by Microsoft. Honestly there's not much point to spinning up a fresh Windows 8.1 or Windows Server 2012 anyways, and if you really want to do my insane workaround, it's an option, you can also use nested virtualization if you need to create a host with a lower windows OS version so you can do things in the old way. I've found many changes which I won't go into any further since these OS are no longer supported. I will say that if you want to have a Hyper-V host as a test lab, you might want to run Server 2022 or Windows 11 21H2, 22H2, or 23H2 if you are dealing with Server 2012 R2 and Windows 8.1 or older OS as VM's. If you are using supported operating systems everything is going to work fine.

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