Fatal error: Uncaught Error: Class 'Symfony\Component\HttpFoundation\HeaderBag' not found in /home/optinadmin/rfl.optin.co.nz/concrete/vendor/symfony/http-foundation/Symfony/Component/HttpFoundation/ResponseHeaderBag.php:21 Stack trace: #0 {main} thrown in /home/optinadmin/rfl.optin.co.nz/concrete/vendor/symfony/http-foundation/Symfony/Component/HttpFoundation/ResponseHeaderBag.php on line 21