Hi,
@RickK5 @HaraldSt
Interpretation of the message is quite right, unfortunately it will be rather difficult, if possible at all to get around it.
Your existing instance of Windows 10, both expects support for Legacy bios boot and OS bootloader itself is also expecting it, so if you just switch to EFI it still shouldn't boot.
Technically-wise it would be simpler to create a new emulated x86 virtual machine, and use Parallels to move or attach hard drive from the old machine to it to access the files.
To try and make this machine start, we would need to: change bios type to EFI for virtual hardware; rewrite the bootloader for Windows 10 to use efi as well, and remove some devices from configuration(which would usually happen automatically, but due to issues with startup it might not).
This is hypothetically possible, but i have to state, that procedure in its entirety, have neither been tested in emulation environment, nor is it guaranteed to go well even in cases with native PC's, but if despite that you wish to attempt you can try the following:
Disclaimer: We generally do not recommend manipulation with virtual machine configuration file directly, and we cannot guarantee how mbr2gpt.exe tool will perform in emulation, or in general, which is why this is not a recommended procedure, but its more of a potential workaround in principle.
Backup the virtual machine before attempting any changes mentioned below to avoid potential data loss.
Note: If you happen to have access to an Intel Mac, it somewhat simplifies things, you just need to start the virtual machine in question in Parallels Desktop 19 or below and use
https://learn.microsoft.com/en-us/windows/deployment/mbr-to-gpt this tool in command line, e.g: mbr2gpt /convert /allowFullOS
1. Backup the virtual machine.
2. Right-click on the machine in Control Center > Show in Finder.
3. Right-click on virtual machine > Show Package Contents > open config.pvs in text editor.
4. Locate and change the following line:
<Bios dyn_lists="" EfiEnabled_patch="">
<EfiEnabled>0</EfiEnabled>
<EfiSecureBoot>0</EfiSecureBoot>
To:
<Bios dyn_lists="" EfiEnabled_patch="">
<EfiEnabled>1</EfiEnabled>
<EfiSecureBoot>0</EfiSecureBoot>
5. Save and close the file > Open the virtual machine configuration > Hardware > remove
USB and
Sound devices by selecting them and clicking "
-" | otherwise attempt to start will throw another error.
5.1: Also it might be required to manually change cpu count to 1 under CPU&Memory.
5.2: Remove system flags if you have set them previously.
6. Download Windows 10 bootable installation iso and mount it in the virtual machine.
7. Start the machine using GUI or terminal command.
8. It will start in installation environment. Use Shift+F10 to open command line interface and attempt to use
https://learn.microsoft.com/en-us/windows/deployment/mbr-to-gpt this tool manual to convert your system loader from MBR to GPT.
We would appreciate feedback should you choose to try this approach, if it can be successful, but given its not obvious and lack of guarantees its understandable if you elect not to.
Click to expand...
