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I recently upgraded a Ubuntu box (a rackmount server) from 20.04 to 22.04. However, the "grub" boot menu kept listing kernel 5.4.0-40 as the default kernel entry regardless what I did - and I've tried many different things

  • run update-grub
  • run grub-install --target=.. /boot/efi
  • disable UEFI boot and only allow legacy mode in the BIOS
  • remove the ubuntu folder inside /boot/efi/
  • umount /boot/efi and disable it from /etc/fstab
  • or even completely delete the /dev/nvme0n1p1 partition that was mapped to /boot/efi

regardless what I did, the boot menu is UNCHANGED! I don't know what was the issue. /boot/grub/grub.cfg clearly shows the 5.15 and 5.17 kernels as the top two options that I installed as part of the 22.04 upgrade, but they could not be shown and used.

I also installed efibootmgr and run efibootmgr -r, it complains "EFI variables are not supported on this system".

can someone let me know what was wrong? how can I update the boot menu?

FangQ
  • 387

1 Answers1

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I am going to answer my own question - for some reason, grub-install failed to update /boot/efi/EFI/ubuntu/grub.cfg even after using

grub-install --target=x86_64-efi --efi-directory=/boot/efi --boot-directory=/boot

the problem is somewhat like this post, except that the grub.cfg file was unchanged after the command.

I think a simply solution could have been copying /boot/grub/grub.cfg to overwrite /boot/efi/EFI/ubuntu/grub.cfg, however, since I deleted the ubuntu folder and even the partition during my test, I ended up re-creating the partition (/dev/nvme0n1p1) from gparted and reinstalling the efi boot folder following this post using a live-USB drive (Xubuntu 22.04).

after mounting all drives and chroot, I ran the same grub-install command above, and the updated kernel list are shown afterwards.

I still don't fully understand why the old /boot/efi/EFI/ubuntu/grub.cfg could not be updated. The Ubuntu on the rack server was installed by the factory. I also have no idea why the system still boots with the old EFI grub menu even after deleting the efi partition.

FangQ
  • 387