Fatal error: Uncaught Error: Call to undefined function is_user_logged_in() in C:\Users\Administrator\OneDrive\AlexCD Backup\Dokumente\Trabajo\Web Developer\LibreriaACD\WP\Custom Fields Frontend Update-Save Form.php:7 Stack trace: #0 {main} thrown in C:\Users\Administrator\OneDrive\AlexCD Backup\Dokumente\Trabajo\Web Developer\LibreriaACD\WP\Custom Fields Frontend Update-Save Form.php on line 7