After update – Problem

Hello,

After I upgrade from version 1.7 to 2.1, the following message appears at the top, in matches.

“y() expects parameter 1 to be a valid callback, class ‘Arcane_TeamWars’ does not have a method ‘on_load_any’ in /home/…/public_html/site/wp-includes/class-wp-hook.php on line 286“