Question: disk is not fixed mbr?
Answer: The selected disk is not a fixed MBR disk. The ACTIVE command can only be used on fixed MBR disks. ... However, the active command only works when your system disk is MBR style, as UEFI has no concept of the active partition. So, for this reasons, the same error can occur if you use the INACTIVE command on UEFI/GPT system.