Fatal error: Uncaught Error: Class "Symfony\Component\Serializer\Normalizer\AbstractNormalizer" not found in /home/robertdr/concrete9.robertdrake.co.uk/updates/concrete-cms-9.4.1-remote-updater/concrete/vendor/symfony/serializer/Normalizer/JsonSerializableNormalizer.php:22 Stack trace: #0 {main} thrown in /home/robertdr/concrete9.robertdrake.co.uk/updates/concrete-cms-9.4.1-remote-updater/concrete/vendor/symfony/serializer/Normalizer/JsonSerializableNormalizer.php on line 22