Lets say you want to migrate your system to a new hard drive.
Of course the best practice is to buy a hard drive with the exact same size. This will save you problems.
I think instead of changing the files where disk UUIDs reside just swap UUIDs between the old and new disk.
invalid partition -- table wrong signature 0
This means something went wrong with the partition table and you want to use fdisk to write a valid partition table.