Cloned a disk to ssd. It’s MBR / BIOS based.

Target system is EFI only.

Trying to do mbr2gpt but mbr2gpt not happy because I chose not to clone the partition that held the BIOS/legacy boot files.

Bit of a chicken and egg situation.
mbr2gpt can’t find MBR/BIOS stuff to convert from, and bcdboot /s won’t install MBR/BIOS stuff because the environment is EFI.

solution:

bcdboot c:\windows /f bios /s c:

..then..
mbr2gpt /convert /disk:0