Fatal error: Uncaught ArgumentCountError: mysqli_insert_id() expects exactly 1 argument, 0 given in /var/www/html/add_to_cart.php:14 Stack trace: #0 /var/www/html/add_to_cart.php(14): mysqli_insert_id() #1 {main} thrown in /var/www/html/add_to_cart.php on line 14