Re: Database version Problem (2->3)
Check that you are using 3.1. Otherwise, tikiwiki is reporting that a new Tiki version (3.1) exists, and you might be having 3.0.
HTH
In any other case, you are hitting a (weird) error that most of us are not having, afaik. You could report the bug (if so) to http://dev.tikiwiki.org