That's by design to prevent you from installing a bootloader on a system where you have no kernel that will boot.
** Changed in: grub2 (Ubuntu) Status: Confirmed => New ** Changed in: grub2 (Ubuntu) Status: New => Opinion -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1788727 Title: upgrade crashing due to unsigned kernels To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/1788727/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs