diff --git a/src/Bundle/ChillMainBundle/Serializer/Normalizer/DateNormalizer.php b/src/Bundle/ChillMainBundle/Serializer/Normalizer/DateNormalizer.php
index e17c0120c..2493b1794 100644
--- a/src/Bundle/ChillMainBundle/Serializer/Normalizer/DateNormalizer.php
+++ b/src/Bundle/ChillMainBundle/Serializer/Normalizer/DateNormalizer.php
@@ -89,6 +89,8 @@ class DateNormalizer implements ContextAwareNormalizerInterface, DenormalizerInt
                     'long' => $formatterLong->format($date),
                 ];
         }
+
+        throw new UnexpectedValueException("format not supported: {$format}");
     }
 
     public function supportsDenormalization($data, $type, $format = null): bool