[Bug 1848797] Re: After upgrading to 19.10, boot screen shows: "Error: symbol 'grub_file_filters' not found."

[Ahmad Gharbeia أحمد غربية]

I faced this issue while upgrading a cloud-based system from 18.04 to
20.04.

Naturally I had created a snapshot of the system before attempting the
upgrade it, so when the upgraded system failed to boot, and after having
read much of what may have caused it here and elsewhere, I restored the
snapshot, re-performed the upgrade, and before rebooting, I re-installed
grub and issued an update-grub command.

I'm blind guessing that in my case it had to do with the mapping of the
virtual system volume between the guest system and its host/hypervisor.
Somewhere in the upgrade grub misses where it should install/update
itself.

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https://bugs.launchpad.net/bugs/1848797

Title:
  After upgrading to 19.10, boot screen shows: "Error: symbol
  'grub_file_filters' not found."

Status in grub2 package in Ubuntu:
  Confirmed
Status in grub2 source package in Eoan:
  Confirmed

Bug description:
  After upgrading to 19.10 the boot screen shows the following error:

  Error: symbol 'grub_file_filters' not found.
  Entering rescue mode...

  I could fix it after i booted Ubuntu 19.10 live and used the chroot
  repair method as described here
  https://wiki.ubuntuusers.de/GRUB_2/Reparatur/#chroot-Methode (german)

  Workaround
  ----------
  From https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/1848797/comments/18
  "In any case, right now the best thing to do to repair is to boot from a Live image (USB or CD-ROM), and follow the steps in https://help.ubuntu.com/community/Grub2/Installing#via_ChRoot to repair GRUB by hand, or reinstall."

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