The only thing that comes to mind is that maybe the device node doesn't exist in /target for some reason (this error message is from grub- install run inside the chroot).
-- installer crashed: GrubInstaller failed with code 1 https://launchpad.net/bugs/71627 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
