This bug bit me pretty hard: My Ubuntu 20.04 laptop updated via unattended-upgrades. Then it lost power due to last week's derecho. Now the OS won't boot.
Anyway, FWIW, I think OP's # dpkg-reconfigure grub-pc advice applies to MBR installations only. If you have a modern EFI installation I think you need dpkg-reconfigure grub-efi-amd64 instead.
This bug bit me pretty hard: My Ubuntu 20.04 laptop updated via unattended- upgrades. Then it lost power due to last week's derecho. Now the OS won't boot.
Anyway, FWIW, I think OP's # dpkg-reconfigure grub-pc advice applies to MBR installations only. If you have a modern EFI installation I think you need dpkg-reconfigure grub-efi-amd64 instead.