Fatal error: Uncaught Error: Interface 'Symfony\Component\Serializer\Normalizer\NormalizerInterface' not found in /home/devmecseminars/public_html/mec/vendor/symfony/serializer/Normalizer/DateIntervalNormalizer.php:23 Stack trace: #0 {main} thrown in /home/devmecseminars/public_html/mec/vendor/symfony/serializer/Normalizer/DateIntervalNormalizer.php on line 23