Fatal error: Uncaught Error: Call to undefined function Members\Admin\add_action() in C:\xampp\htdocs\wp-content\plugins\members\admin\class-meta-box-custom-cap.php:41 Stack trace: #0 C:\xampp\htdocs\wp-content\plugins\members\admin\class-meta-box-custom-cap.php(104): Members\Admin\Meta_Box_Custom_Cap->__construct() #1 C:\xampp\htdocs\wp-content\plugins\members\admin\class-meta-box-custom-cap.php(110): Members\Admin\Meta_Box_Custom_Cap::get_instance() #2 {main} thrown in C:\xampp\htdocs\wp-content\plugins\members\admin\class-meta-box-custom-cap.php on line 41