Package: grub-common Version: 2.02-2 Severity: grave I have my root filesystem on ZFS. I'm using a ZFS pool's root dataset (rpool) as opposed to a sub-dataset (eg. rpool/foo or rpool/foo/bar).
update-grub calls calls /etc/grub.d/10_linux which sets the root=ZFS= parameter for grub/initrd. In this case, it sets it as root=ZFS=rpool/. Note the trailing slash. This is invalid and makes the system unbootable. I already filed this bug at https://savannah.gnu.org/bugs/?52746 . But that bugtracker looks completely abandoned for months. I'm pretty sure it only needs a small fix to remove extra trailing slashes.