do-release-upgrade command left /dev/nvme1 unbootable on 20.04 LTS

[Colin Watson]

On Thu, Jun 17, 2021 at 02:38:15PM -0400, Eric Wood wrote:
> The other system got into an infinite loop during the upgrade script saying
> it had trouble making a boot partition.  So we had to abort the script. 
> This left the system unbootable with this grub error:
> Error: symbol 'grub_file_filters' not found.

This happens on BIOS (non-UEFI) systems where they're configured to
install GRUB to a disk that isn't the one that the system is actually
booting from.  Although it happens on upgrades, it's really more the
fault of whatever configured the system that way in the first place than
of the upgrade process itself.

> So we used  https://help.ubuntu.com/community/Boot-Repair and got the broke
> system running very easily.

boot-repair may manage a one-time fix, but if I were you I would not
rely on it having fixed the problem at its root.  To fix the problem at
its root, you need to run this:

  sudo dpkg-reconfigure grub-pc

... and (unless you know better) change the answer to the "GRUB install
devices" question to install GRUB to the boot record of all your drives,
so in your case /dev/nvme0n1 and /dev/nvme1n1; that way it doesn't
matter which one of those the BIOS decides to boot from.  You can leave
the answers to all the other questions unchanged.

> I don't know why we installed Ubuntu on nvme0 on one system and nvme1 on the
> other.   Maybe the BIOS settings were different at install time.  Bit, I'm
> now noticing that /dev/nvme1n1p1 was set up as 1Meg BIOS boot partition
> instead of a EFI system parition - another thing  we may have screwed up
> when setting up these two identical boxes.

This machine was evidently set up using BIOS rather than UEFI, which is
why that happened.  If you intended them to be identical, then this is a
pretty major difference.  To fix that, you'd need to reinstall this
system, and make sure that you're booting the installer in UEFI mode
(which is typically a matter of making sure that the system firmware is
configured to boot removable media in UEFI mode rather than what it may
call something like "legacy" or "CSM" mode).

-- 
Colin Watson (he/him)                              [cjwatson at ubuntu.com]