Digging around bugs reported on bugs.launchpad, i've seen a bunch of reports rised by users (mostly new comers i suppose) not knowing about versions having reached EndOfLife.
Most of these reports was against "solftware-center" : like, "got server error 500" or "i does not understand why software-center cant download even if my network works with the browser". So launchpad get flooded by invalid reports.
Users have to be aware of such a case : the different tools (installer/updater) should detect the different EOL version, and be able to display a popup message saying something like "that version is no more available, choose a newer ubuntu release"; on the other hand Apport also need to refuse such reports.
Related packages : apt, synaptic, software-center (for the gnome world; but i suppose the other DEs are also concerned)
<https:/ /wiki.ubuntu. com/SoftwareUpd ates#upgrades>: "If no updates are available but a new version of Ubuntu is, the alert should have “Upgrade…” and “OK” buttons (replacing the separate “Ubuntu {version} Upgrade Available” dialog), and text depending on the situation..."