Package: x2goserver Version: 4.1.0.3
My server was rebooted during the weekend and x2golistsessions still showed a session, which of course not valid anymore. But x2goclient failed to open a connection to that server, all it reported was "session <old_sessionid> terminated". After running x2goterminatesession everything worked normally again.
So I propose to cleanup the list of running sessions during bootup to prevent such weird problems from happening.