This was affecting my system too. /dev/sdb was the descriptor for a external drive that's no longer present in the system. I only connect it sometimes.
My /boot/grub/device.map looked like this: (hd0) /dev/sda (hd1) /dev/sdb I removed the second line and the problem disappeared. -- error: cannot open `/dev/sdb' while attempting to get disk size - grub2 update https://bugs.launchpad.net/bugs/425112 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs -- universe-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/universe-bugs
