Recently a friend asked me if I could help him with his Ubuntu as he faced some weird problems. Looking up his version made me realize he fell a bit out of time a few years ago: He had Ubuntu 13.04
A few updated-commands later I was bombed by "Ign" and "404" errors and had quite a hard time finding useful information how to move that old software into modern times. In most forums it was suggested to just ditch it and just install a fresh Ubuntu. (The problem was solved after the Live-USB suggested to do the whole upgrade)
What should I have done in that situation and why is it so difficult to bring such old systems up to date?
Edit:
No, I am not interested in how to upgrade the old Ubuntu. I just want to know why a simple update/upgrade/dist-upgrade command doesn't work any more (If moving to the archive servers it just remains as it is, but a reasonable update is not happening).
Why is also do-release-upgrade not doing any useful job?