Convert Windows 11 BIOS VM to Windows 11 Compliant UEFI VM

[wpilgri88]

I have a Windows 11 x64 insider edition Virtual machine that will no longer upgrade to the latest Windows 11 build because it is no longer compliant and Microsoft seems to now be checking requirements.  Secure boot and TPM are not enabled and the current VM is setup with Firmware Type=BIOS.  As the VM is customized to my liking I am loath to just delete it and start clean so am wondering:

Q:  What is the best way to "convert" a Firmware Type=BIOS based VM to a working Firmware Type=UEFI based VM?  Clearly you can't just change Firmware Type as it won't boot so am hoping there is another process where I can preserve the Windows customizations I have an import them into a new VM.

I am using the up to date version of Workstation Pro 16.

Thank You

[bluefirestorm]

I don't know about Windows 11. But with Windows 10 (starting with 1703), there is a tool called mbr2gpt.

https://docs.microsoft.com/en-us/windows/deployment/mbr-to-gpt

After you convert the boot disk from MBR to GPT, you can then switch to UEFI.

WARNINGS:

mbr2gpt can only convert when there are 3 partitions on the disk; anything more it won't do it. You might have to use something like gparted to delete and move partitions around if the virtual disk has more than 3 partitions so as to get MBR2GPT tool to work.

Adding a virtual TPM to the VM will require the VM to be encrypted (thus encrypting the virtual disks as well). It is best the virtual disks are preallocated if they are to be encrypted to prevent runaway growth that the virtual disks occupy on the host storage

[wpilgri88]

Thank you very much for the reply and guidance.  I will give it a try and report back.

Thanks again!

[wpilgri88]

I just wanted to reply that yes indeed. mbr2gpt worked like a charm.....that is after I fumbled and made sure my disk conformed to the requirements for mbr2gpt, which meant no logical partitions in my case.

Thanks again for the help!

[hauke0815]

mbr2gpt worked fine and quick, but now I can't boot the vm any more. It tries a network boot although the hard drive is selected as boot device.

[70tas]

Did you convert your boot partition, and encrypt your system prior to enabling UEFI?

if not reverse UEFI and see if you can reboot it. If so, use the admin cod command:

mbr2gpt /convert /disk:0 /allowfullOS

then enable UEFI and secure boot.