Rebooted and reinstalled. Using different order for selecting ESP/efi partition it worked without error on not using sda, but installed to ESP on sda. Install log showed this:
Feb 15 20:23:36 ubuntu grub-installer: info: Installing grub on '/dev/sdb' Feb 15 20:23:36 ubuntu grub-installer: info: grub-install does not support --no-floppy Feb 15 20:23:36 ubuntu grub-installer: info: Running chroot /target grub-install --force "/dev/sdb" Feb 15 20:23:36 ubuntu grub-installer: Installing for x86_64-efi platform. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1816184 Title: Disco ubiquity crash To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/ubiquity/+bug/1816184/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
