Post History

In Debian derivatives (of which Ubuntu is one), and more generally those distributions that use the Debian `apt` package manager tool suite, for packages to be "kept back" during an upgrade means that upgrading those packages would require some change that the requested type of upgrade is prevented from performing.

For example, if a package upgrade would pull in a new package, then `upgrade` won't upgrade that package (because `upgrade` won't install any new packages), and consequently any further packages that depend on the kept-back package having been upgraded will also be kept back.

To perform such an upgrade, depending on whether you prefer to use `apt` or `apt-get`, you need to use either `apt full-upgrade` or `apt-get dist-upgrade` respectively.