sudo update-grub
/usr/sbin/grub-probe: error: failed to get canonical path of `aufs'.

ubuntu@ubuntu:~$ sudo apt-get install grub
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package grub is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
However the following packages replace it:
  grub2-common grub-pc grub-efi-ia32 grub-efi-amd64

E: Package 'grub' has no installation candidate