Comment 2 for bug 2040187

Same for the now official upgrade. Regardless updating from commandline (do-release-upgrade) or via graphical application (update-manager). After having finished upgrading the system will boot into UEFI-Menu, not finding grub to boot.

The upgrade works, if the system is installed on ext4 with lvm. After upgrading the system will boot into Ubuntu 23.10.

The upgrade does not work, if the system is installed on zfs with root on zfs. After upgrading the system will boot into UEFI-Menu without any chance to ever start Ubuntu 23.10 -- grub is missing.

The upgrade does work partly, if the system uses an ext4 partition for boot, having /root on zfs. The system will boot into maintenance mode, unable to mount zfs-root. Looks like the modules for zfs are missing from the kernel.

The upgrade does work, even with zfs only systems if it is done from a booted life system.