When you try to convert Windows 10 to UEFI, so partition from MBR to GPT, MBR2GTP fail.
The command return this error:
Info ESP partition size will be 104857600
Info MBR2GPT: Validating layout, disk sector size is: 512 bytes
Error Validate Layout: Too many MBR partitions found, no room to create EFI system partition.
Error Disk layout validation failed for disk 0
Info MBR2GPT: Partition information at error point
Windows 10 1703 and above
The mbr2gpt disk conversion tool need three conditions for the validation of disk layout:
- Admin rights
- One of physical disk with boot partition MSR and OS partition
- The validation allows normally one of additional partitions, often it's recovery partition
If you have more than three partition validate will fail.
Check this with Get-Partition cmdlet
In this case we have too partition, so we have to find the Windows Recovery Environment (Windows RE) partition with the command ReAgentc /info
Now we have to remove the "exceed" partition (partition 4)
mbr2gpt /convert /disk:0 /allowfullos