[Plugin: Events Manager] WP_User:WP_User undefined method

If you get the error WP_User:WP_User undefined method in classes/em_person.php line 24 it is because of the newer

// parent::WP_User($person_id);
instead use
parent::__construct($person_id);

As of PHP 5.3.3, methods with the same name as the last element of a namespaced class name will no longer be treated as constructor. This change doesn’t affect non-namespaced classes.

http://php.net/manual/en/language.oop5.decon.php