This is almost exactly the same as What do I select for “GRUB install devices” after an update? - or perhaps it isn't, hence asking, as I'm running Ubuntu on a Virtualbox machine via Vagrant.
I was unable to update packages, so I ran
sudo apt-get update then
sudo apt-get dist-upgrade. It appeared with the following message:
The GRUB boot loader was previously installed to a disk that is no longer present, or whose unique identifier has changed for some reason. It is │ │ important to make sure that the installed GRUB core image stays in sync with GRUB modules and grub.cfg. Please check again to make sure that GRUB is │ │ written to the appropriate boot devices. │ │ │ │ If you're unsure which drive is designated as boot drive by your BIOS, it is often a good idea to install GRUB to all of them. │ │ │ │ Note: it is possible to install GRUB to partition boot records as well, and some appropriate partitions are offered here. However, this forces GRUB to │ │ use the blocklist mechanism, which makes it less reliable, and therefore is not recommended. │ │ │ │ GRUB install devices: │ │ │ │ [ ] /dev/sda (85899 MB; VBOX_HARDDISK) │ │ [ ] - /dev/sda1 (254 MB; /boot) │ │ [ ] /dev/dm-0 (84833 MB; precise64-root)
I'm guessing that the first option is the correct one, just as the answer to the other question says, but I don't like guessing! I'd be really grateful for any help or insight.