Comment 0 for bug 1807043

When rewriting sources.list entries the release-upgrader doesn't check to see if the distribution to which the system is being upgraded is supported by the archive / PPA. This results in the following error message:

A problem occurred during the update. This is usually some sort of
network problem, please check your network connection and retry.

E:The repository 'http://ppa.launchpad.net/team-xbmc/ppa/ubuntu
cosmic Release' does not have a Release file.

If the release-upgrader were to actually check if the release were supported then that specific sources entry could be disabled and the upgrade may be able to proceed.