Deleting partitions on GPT leaves a gap. Windows boot doesn't like this.
If I delete a partition that is not the last partition on a GPT disk, it blanks out that entry leaving a gap in the array.
One of the stages in the Windows boot process appears to not see partitions after such a gap.
So if for example I have the following partitions:
(EFI Boot partition)
Linux /
Windows system partition
created in that order and so listed in the GPT entries in that order, and use Gparted to delete the Linux partition, Windows will then fail to boot claiming that it cannot find the boot device.
In my particular case I was able to use sfdisk
dump / load to compactify the GPT entries. But I'm thinking that Gparted should have a way to do this, which I was not able to find, and perhaps should also present a warning if something that looks like a Windows system partition is after a gap in GPT entries.
I saw this with the Gparted version from System-Rescue 7.01, which is Gparted 1.1.0 . I don't see anything that looks relevant in the Gparted 1.2.0 release notes.