In the question on askubuntu you mention having installed stuff from a PPA, that you now can't find. If it was disabled by the upgrade then the details should still be in /etc/apt/ - I think either commented out in sources.list or a renamed file under sources.d

 

I usually find aptitude better than apt-get when running into problems like this - it will give you options to get things working (eventually one of them should be to remove the things from the PPA that are causing problems).

 

Robert