Windows 10: Upgrading to Windows 11, using mbr2gpt to convert boot drive to gpt doesn't work. Wrong...

Hello,I'm writing because I'm having trouble upgrading to Windows 11 from Windows 10, specifically with regards to the use of mbr2gpt in coverting my hard drives to support UEFI.I've attempted to follow numerous tutorials but I'm always met with the same error message in Command Prompt "Disk layout validation failed for disk 0". My logs in setupact.log are as follows:2025-06-22 20:54:24, Info MBR2GPT was explicitly asked to run in full OS mode. 2025-06-22 20:54:24, Info MBR2GPT: Attempting to validate disk 0 2025-06-22 20:54:24, Info

:)

 

Partition Prerequisites for converting to GPT using MBR2GPT

Delete step 3. Step 4 will convert the system drive to GPT and convert the System Reserved partition (which legacy BIOS boots from) to an EFI System Partition (which UEFI boots from). After MBR2GPT completes that conversion, your computer will no longer boot in legacy BIOS mode. You will need to set the UEFI firmware to boot in UEFI mode before the computer will boot into the OS again.

After the system drive is converted to GPT and is booting in UEFI mode, then you can convert the other physical drives to GPT if you want to using third party partitioning programs like MiniTool Partition Wizard or AEOMI Partition Assistant.

After you backup your drive, presumably with a program like Macrium Reflect, make sure to also create the rescue drive (USB flash drive) with the same program so that you can boot the computer from that to restore the backup image if you need to. The rescue drive should be bootable in both legacy BIOS and UEFI modes.

I'll work on the steps to do the conversion manually and setting up your own EFI System Partition from scratch. I'm going to make a backup of my computer and do it myself to make sure I get the steps correct.

 

Converting disk from MTR to GPT and installing Windows 11

Hi, I am Dave, I will help you with this.

The steps to convert the drive from MBR to GPT using the built-in mbr2gpt tool on the Windows system drive are provided on this link, that process is not destructive to your data, but you do need a backup of your personal files just in case the process goes wrong.

https://learn.microsoft.com/en-us/windows/deplo...

 

Issues using MBR2GPT for Windows 11 Upgrade

I am trying to use MBR2GPT to 'Enable Secure Boot' as the last remaining item before upgrading to Windows 11. I have been having issues doing this, please see the image of the command prompt errors when trying this as well as my current Disk Management.





Command Prompt text:

C:\WINDOWS\system32>mbr2gpt /convert /disk:0 /allowfullos



MBR2GPT will now attempt to convert disk 0.

If conversion is successful the disk can only be booted in GPT mode.

These changes cannot be undone!



MBR2GPT: Attempting to convert disk 0

MBR2GPT: Retrieving layout of disk

MBR2GPT: Validating layout, disk sector size is: 512 bytes

Cannot find OS partition(s) for disk 0



C:\WINDOWS\system32>mbr2gpt /convert /disk:1 /allowfullos



MBR2GPT will now attempt to convert disk 1.

If conversion is successful the disk can only be booted in GPT mode.

These changes cannot be undone!



MBR2GPT: Attempting to convert disk 1

MBR2GPT: Retrieving layout of disk

MBR2GPT: Validating layout, disk sector size is: 512 bytes

Disk layout validation failed for disk 1