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It's far from clear how grub package updates work on Ubuntu
Recently I ran across (and eventually reported) an issue on pre-beta Ubuntu 24.04 where a grub package update would fail for systems with software RAID root disks and BIOS MBR booting. The specific error was that grub-install could not install the new version of GRUB's boot-time code on '/dev/md0', the (nominal) device of the root filesystem, reporting an error to the effect of: grub-install: warning: File system `ext2' doesn't support embedding.
One of the puzzling things about this entire situation is that the exact same configuration works on Ubuntu 22.04 and there are no obvious differences between 22.04 and 24.04 here. Nor does scanning and searching either version of the script provide any smoking guns in the form of, for example, mentions of 'md-'. PS: after much delving into things using various tools and the fact that I have various scratch virtual machines available, I now believe that the answer is that Ubuntu 20.04 and 22.04 don't run grub-install at all when the grub package (for MBR booting) is updated.
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