Comment 3 for bug 2041739

Had the same issue after upgrading to Ubuntu 23.10. Tried repairing grub multiple times in chroot after booting from a live USB. Even tried to roll back to a zfs snapshot from before the upgrade, which also did not work.

Was finally able to recover from this after finding this bug report with the mention of recreating the bpool.

I created a script to prepare the chroot to be able to speed up the tries to fix grub. Since I'm running zfs on root with encryption, it was taking too much effort to do this manually every time. I've included the script which might be useful for anyone else encountering this issue. You will have to be aware of your partition layout and adjust the script accordingly.