Upgrade to 2.8.+ went smooth. When i click on any category of courses i get :
Category path order is incorrect and/or there are missing categories
and
Notice: Undefined offset: 17 in /var/www/html/moodle/lib/navigationlib.php on line 1699
Notice: Trying to get property of non-object in /var/www/html/moodle/lib/navigationlib.php on line 1700
Notice: Trying to get property of non-object in /var/www/html/moodle/lib/navigationlib.php on line 1704

Courses seem to work fine. I can't add new courses or delete one.