If you are having the problem in the bug you linked, then that is the problem, and not what you described here.
** Changed in: grub2 (Ubuntu) Status: New => Invalid -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1072794 Title: Win partition needs to be mounted for an update-grub to discover it To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/1072794/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs