Fatal error: Uncaught Error: Class 'Symfony\Component\Serializer\Normalizer\AbstractNormalizer' not found in /srv/www/c5www/html/updates/concrete5-8.5.1/concrete/vendor/symfony/serializer/Normalizer/JsonSerializableNormalizer.php:22 Stack trace: #0 {main} thrown in /srv/www/c5www/html/updates/concrete5-8.5.1/concrete/vendor/symfony/serializer/Normalizer/JsonSerializableNormalizer.php on line 22