When updating to a new version of Ubuntu, it is generally recommended to delete the
$HOME/.texmf-var folder (it will be automatically recreated with up-to-date information on the next tex run).
The TeX Live packages contained in many Ubuntu/Debian releases are slightly out of date and do not contain the
tlmgr tool to update packages. Thus many users ignore these packages and install TeX Live directly.
There is a Stack Exchange site dedicated to Ubuntu which is a good place to ask Ubuntu-related questions.