Please upgrade to 2.2 here.
The 2.0 and 2.1 branches are no longer being updated.
Following carefully and correctly this tutorial http://vanillaforums.org/discussion/12740/vanilla-2-upgrading-tips
A fatal error is pull out saying:
Fatal error: Cannot create references to/from string offsets nor overloaded objects in ../library/core/class.thememanager.php on line 87
What do I have to do in order to fix it up?
thanks in advance.