The following packages have been kept back

In Ubuntu (or Debian and other derivatives), you might observe the following message when performing sudo apt-get upgrade.

The following packages have been kept back

To get rid of this one, do:

$: sudo apt-get install <package name(s)>

For example, below was one of the error messages I am getting:

The following packages have been kept back
    linux-generic linux-headers-generic linux-image-generic

To fix this do:

$: sudo apt-get linux-generic linux-headers-generic linux-image-generic