Fatal error: Uncaught Error: Call to undefined function add_action() in C:\xampp\htdocs\wp-content\plugins\members\addons\members-role-levels\admin\class-meta-box-level.php:40 Stack trace: #0 C:\xampp\htdocs\wp-content\plugins\members\addons\members-role-levels\admin\class-meta-box-level.php(173): Members_Role_Levels_Meta_Box_Level->setup() #1 C:\xampp\htdocs\wp-content\plugins\members\addons\members-role-levels\admin\class-meta-box-level.php(180): Members_Role_Levels_Meta_Box_Level::get_instance() #2 {main} thrown in C:\xampp\htdocs\wp-content\plugins\members\addons\members-role-levels\admin\class-meta-box-level.php on line 40