Windows 10: How to copy boot files from my Windows 11 C Drive to the VHDX Hyper V Drive?

I want to install Windows 11 on Hyper-V, so I'm doing it manually DISM. I can do that part, but how can I add the boot files to the Virtual Hard Drive by copying from my actual C Drive?

:)

 

How to boot into bootable differencing vhdx in Hyper-V

Hello,

I am trying to upgrade my boot to VHD VHDX to the latest Windows 10 update using this terrific tutorial from @Kari: Native boot Virtual Hard Disk - How to upgrade Windows

However, I am having trouble getting the vhdx to boot in Hyper-V. Everything seems to work as expected, but when I get to step 1.18, Hyper-V gives a "The boot loader did not load an operating system" error booting off the VHDX.

I wonder if the boot files are getting created appropriately. When I run

c:\windows\system32\bcdboot c:\windows /s c:

it says it worked correctly, but if I run

bcdedit /v

after that, it says "The boot configuration data store could not be opened. The requested system device cannot be found."

The c: drive is available via the windows installation command prompt.

Other possibly useful information:
- The VHDX is a differencing disk, and the parent VHDX file is read-only
- The VHDX was created in Windows and initialized for Windows install using DISM. It was not created in Hyper-V.

Any ideas? Thanks in advance.

 

How to boot into bootable differencing vhdx in Hyper-V

Hi there

You can try this method (from the Ms documentation) which doesn't need HYPER-V features so should work on any Windows version.

https://docs.microsoft.com/en-us/win...-the-boot-menu

Cheers
jimbo

 

Reusing vhdx (native boot) in Hyper-V

Thanks for the suggestion.

I created a new machine in hyper-v, tried to install the latest insider builds but it wouldn't boot from them either. Only 17134.1 iso worked. So I installed that instead to get the correct vhdx configuration. However it took 1hr20mins!

Tried imaging using macrium, at this point I was fed up with waiting and the time element. Thought there must be an easier way.

Checked the structure of 17134.1 vhdx created in hyper-v, it contained EFI, Windows and Recovery partitions.

Remembered you stating something about my previous vhdx not having correct boot files.
(17760 only contained windows partition, no EFI, MSR or Recovery)

So created a new vhdx (A1) within disk manager, used diskpart following instructions on MSoft website as guidance and adapted to my configuration. https://docs.microsoft.com/en-us/win...ive-partitions

Deployed .wim to the windows (W partition (A1) and applied bcdboot (from A1) to the EFI (S partition on the vhdx (A1). Attached this vhdx (A1) to vm in hyper-v and booted successfully *Biggrin (Tip, rename the EFI to something like "SystemVHD or SysVHD" to avoid confusion)

https://docs.microsoft.com/en-us/win...-the-boot-menu

However, I had an existing vhdx (A2) with build 17760 deployed using dism and installed apps that I wanted to keep then boot in hyper-v to perform the upgrade to 17763. Obviously couldn't create EFI partition since there was one main partition starting from the beginning of the vhdx (A2).

So I created a new vhdx (A3), 1gb (disk management complains about minimum size for gpt drive), gpt, made EFI and MSR partitions, and while the build 17760 vhdx (A2) was mounted in explorer I used bcdboot (from 17760 vhdx (A2)) to write boot files to this recent EFI (S(A3).

Ejected both drives, mounted the EFI vhdx (A3) as SCSI (0) and the 17760 vhdx (A2) as SCSI (1), made sure boot order was EFI (A3) first, 17760 (A2) second in the firmware section of vm properties and managed to boot successfully *Biggrin

Insider upgrade using win update and also from attached iso both initiated and proceeded to install without error.

Due to the slowness of VM I decided its much quicker to deploy wim to vhdx with each new build and go through setup process than inplace upgrade. Tried a few tweaks in VM to allocate more cores and RAM made a noticeable difference but performance still far below VHD native boot not to mention that I have had enough of hyper-v and VMs.

Thanks again.