Comment 73 for bug 1289977

Once again, this report is invalid because it does not describe a defect in the software that needs fixed. Once again, the problem with your installation is that grub-pc/install_devices was not set so the system did not know that it needed to run grub-install to reinstall grub on that disk after upgrading the grub files in /boot/grub.

As Mathias noticed, this happens to "power users". This is because you know enough to be able to install grub yourself, which gets it working at the time, but leaves grub-pc/install_devices incorrect so it will break on upgrade. You need to use dpkg-reconfigure grub-pc instead, so that grub-pc/install_devices will be set correctly and grub-install will be run automatically on upgrade.

Baby, if the installer fails to install grub, then it should file a new bug report about that and we can investigate.