Boot from a USB stick like you are going to install windows
Open the CMD window
Run the following command:
diskpart
list disk
This will give you a list of partitions to choose from. Take not of the one that does NOT have a * in the GPT table and is your C drive
Then run this command:
mbr2gpt /validate /disk:0
(Be sure to put the correct disk number here)
I got a layout error when doing this. turned out it was because there were 4 partitions and mbr2gpt only supports 3. I deleted the Recovery partition and all was good.
If everything checks out ok you can then run this command:
-
mbr2gpt /convert /disk:0
(Be sure to put the correct disk number here)
If success full then reboot and make sure UEFI is the boot type
References:
https://www.windowscentral.com/how-convert-mbr-disk-gpt-move-bios-uefi-windows-10
https://scottiestech.info/2017/11/12/convert-your-windows-10-boot-drive-from-mbr-to-gpt/
https://www.disk-partition.com/windows-10/mbr2gpt-conversion-failed-3889.html