I'm using Ubuntu 12.04, suddenly Ubuntu update manager stopped updating.
At first I thought that, it's a problem with my Internet connection, but I was wrong, because downloading, browsing everything is perfect.
Then I've tried with
to remove my previous lists and update with a new one. Unfortunately, no luck with this, same problem continuing.
sudo rm -vf /var/lib/part/lists/partial/*
Moreover, recently I've tried to add Cinnamon PPA, but it failed to connect with the key server.
Then I've pinged to archive.ubuntu.com, that's perfectly OK.
I don't know what's the problem. Please help anyone.
Thanks in advance.