core/modules/serialization/src/Normalizer/ConfigEntityNormalizer.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/core/modules/serialization/src/Normalizer/ConfigEntityNormalizer.php b/core/modules/serialization/src/Normalizer/ConfigEntityNormalizer.php
index 344bcc3..dd766ce 100644
--- a/core/modules/serialization/src/Normalizer/ConfigEntityNormalizer.php
+++ b/core/modules/serialization/src/Normalizer/ConfigEntityNormalizer.php
@@ -18,7 +18,7 @@ class ConfigEntityNormalizer extends EntityNormalizer {
    * {@inheritdoc}
    */
   public function normalize($object, $format = NULL, array $context = []) {
-    return $object->toArray();
+    return array_diff_key($object->toArray(), ['_core' => TRUE]);
   }
 
 }