I have Quantal (upgraded recently), and can confirm the problem.
In fact the problem are non-english characters. When you upgrade, upgrade tool would disable old sources and add commnet they are disabled. In slovenian language comment is like: "onemogočeno ob nadgradnji na quantal". It contains slovenian character "č".
When I changed it to "onemogoceno ob nadgradnji na quantal" ("c" instead of "č"), everything works fine.
It is a nasty bug for all who don't know how to edit sources.list from commandline, because you can not enable, remove or edit disabled sources from GUI tool.
I think solution should be quite trivial, so it would be great if developers could solve that with higher priority.
I have Quantal (upgraded recently), and can confirm the problem.
In fact the problem are non-english characters. When you upgrade, upgrade tool would disable old sources and add commnet they are disabled. In slovenian language comment is like: "onemogočeno ob nadgradnji na quantal". It contains slovenian character "č".
When I changed it to "onemogoceno ob nadgradnji na quantal" ("c" instead of "č"), everything works fine.
It is a nasty bug for all who don't know how to edit sources.list from commandline, because you can not enable, remove or edit disabled sources from GUI tool.
I think solution should be quite trivial, so it would be great if developers could solve that with higher priority.