I’m trying to find a way to reliably convert Windows 10 installations from MBR (BIOS) to GPT (UEFI), but keep running into specific problems.
I recently installed a Samsung 980 M2 SSD on an older Asus H97-Pro motherboard. That PC had a MBR Win10 installation and provided a good opportunity to test said MBR to GPT conversion. Which, as you may have deduced by now, has not been going smoothly. My goal is to get the existing Win10 installation from an MBR sata-ssd to the GPT-formatted 980 and to turn off legacy support on the motherboard (=UEFI only).
I had to upgrade the mobo’s firmware to the most recent version (2906) to make the 980 show up in the BIOS.
I then turned the 980 into a blank MBR disk and copied all Windows partitions from the MBR sata SSD to the 980. (Afterwards, I disconnected the sata SSD.) Converting the 980 in that state from MBR to GPT fails:
- Microsoft’s MBR2GPT fails to validate the drive.
- Converting the MBR drive to GPT in Minitool Partition Wizard 11 (Windows PE) seemed to be more successful, until booting the result ended in a black screen containing only a Windows 10 mouse cursor with a small blue circle (loading animation) on top of it.
Efforts to repair that installation were unsuccessful:
- I tried Macrium Reflect (Windows PE) > fix Windows boot problems, which completed without errors but didn’t solve the issue.
- Boot Repair on a bootable Windows 10 installation thumb drive reported being unable to repair.
The last thing I tried was a fresh Windows installation on the 980, with the mobo set to UEFI only. This resulted in a bootable Windows installation. I then replaced the Windows partition (not touching the other two) with the Windows partition from the MBR installation. Windows booted into automatic repair, which once more reported being unable to repair after.
The exact version of Windows I’m trying to install, as well as that of the existing MBR installation, is Windows 10 Enterprise (N) LTSC 2019. This is in fact a 1809 build that receives updates. 1809 is an older base. Could it be lacking a specific driver for the 980? If so, what would be the most efficient way to add it to an existing installation? Personally I think it’s unlikely, as I have installed this Windows version on NVMe SSD’s before.
What am I missing here? I have been unable to find a solution to this problem in posts on this website as well as others. Mobo is currently set to UEFI only, secure boot disabled, AHCI mode, Intel Rapid Storage off.
