Customized Windows 10 ISO Image results in boot issue with EFI

[Andre Lahrmann]

Hi,

I want to use a customized Windows 10 ISO Image (removed some default apps and re-configured basic settings) for a Windows 10 installation in a VM (HW version 15).

I have to notice that I cannot boot from EFI with this modified ISO image.

I can change this in the VM-setting to "BIOS" instead of EFI, and I can boot and install from this ISO image successfully.

But when I try to change from BIOS to EFI after the OS installation, the already installed VM is not bootable.

Trying to use an unmodified ISO image, I can boot a new VM with EFI successfully.

What can I do to use the customized ISO image when I want to configure EFI in the VM configuration also?

Why is it not possible to boot the installed VM with EFI, when this was installed with BIOS?

Would be great to get some tips.

Thanks and Best Regards,

Andre

[continuum]

The customiziation procedure you used is obviously inappropriate.

Sounds like you used settings that either removed the EFI directory or did not use the correct commandline to rebuild the iso.

[Andre Lahrmann]

Hi,

it seems that you are right.

In fact the installed Windows 10 is an MBR partition.

I found this interesting article: https://www.virtuallyghetto.com/2017/10/tip-from-engineering-use-uefi-firmware-for-windows-10-server-2016.html

I converted the installed VM per MBR2GPT tool to a GPT partition.#

After powering off the VM I changed the setting from BIOS to EFI.

Et voila - I could start this VM successfully!!

So, thanks for your response, and I have learned something new today:-).

Regards,

Andre