I want to upgrade from Kubuntu 11.10 to 12.04 (Precise Pangolin). (Perhaps that's unwise, I realize.) The problem I have is that no matter what I do, the automatic upgrade isn't recognized. Specifically, if I type on the command line, or even I get the message "No new release found". I've inquired about this in various fora, but with no useful results.

So now I have a slightly different question: how is the upgrade notification supposed to work, i.e., what algorithm does it use? What program is looking for a new release? And just what is it looking for?

Back when I was using Ubuntu (through 11.04), there was a setting in the Synaptic Package Manager to "notify of distribution upgrades" (or some such wording). By default it was unchecked.

I would look for something like that in Synaptic (if it's still included) or in whatever passes for Synaptic in today's Ubuntu. Good luck.

Edit: I found this: http://www.ubuntu.com/download/desktop/upgrade

The problem I have is that the upgrade procedure you cited doesn't find any upgrades. The setting you're referring to, I think, is in the Updates section of Synaptic's Settings/Repositories. And it doesn't help.

That's why I'm trying to dig deeper and find out how this thing is actually implemented. The answer probably lies in the source code for do-release-upgrade -- if I could understand it.

Have you taken a look at the man page?
Ubuntu Manpage: do-release-upgrade - manual page for do-release-upgrade : http://manpages.ubuntu.com/manpages/...upgrade.8.html

Yet another weird way Ubuntu differs from Debian.

What is so hard about doing apt-get dist-upgrade?

I've tried do-release-upgrade with just about every option, and it still finds no release. I also reinstalled it, as you suggested, with apt-get. Still the same result.

I may have to resort to looking at the source code, if I can make any sense out of it. Hopefully it's well commented. But I don't know how to retrieve it -- Synaptic has nothing obvious for retrieving the source code for update-manager-core, assuming that's the package I need to look at.