Warning: session_start(): Session cannot be started after headers have already been sent in C:\xampp\htdocs\tienda\config\db.php on line 3 Warning: session_start(): Session cannot be started after headers have already been sent in C:\xampp\htdocs\tienda\ajax\is_logged.php on line 2 Warning: Undefined variable $_SESSION in C:\xampp\htdocs\tienda\ajax\is_logged.php on line 3 Warning: Trying to access array offset on value of type null in C:\xampp\htdocs\tienda\ajax\is_logged.php on line 3 Warning: Cannot modify header information - headers already sent by (output started at C:\xampp\htdocs\tienda\config\db.php:1) in C:\xampp\htdocs\tienda\ajax\is_logged.php on line 4