plugin don't work after update

after updating to the last WP i got this message Warning: array_keys() [function.array-keys]: The first argument should be an array in /web/htdocs/www.datipersonali.info/home/genuovo/wp-includes/class-wp.php on line 420 and i can see only the site frontpage

http://ww.wp.xz.cn/plugins/amr-users/