Fatal error: Uncaught Error: Call to undefined function add_action() in /home/ioscotland/public_html/wp-content/plugins/cornerstone/includes/menu-item-custom-fields/menu-item-custom-fields.php:61 Stack trace: #0 {main} thrown in /home/ioscotland/public_html/wp-content/plugins/cornerstone/includes/menu-item-custom-fields/menu-item-custom-fields.php on line 61