Fatal error: Uncaught Error: Class "Drupal\serialization\Normalizer\ComplexDataNormalizer" not found in /home/qcsvlel/www/core/modules/serialization/src/Normalizer/EntityNormalizer.php:15 Stack trace: #0 {main} thrown in /home/qcsvlel/www/core/modules/serialization/src/Normalizer/EntityNormalizer.php on line 15