diff --git a/core/lib/Drupal/Core/Entity/Plugin/Validation/Constraint/ValidReferenceConstraintValidator.php b/core/lib/Drupal/Core/Entity/Plugin/Validation/Constraint/ValidReferenceConstraintValidator.php
index 174139e..67e752b 100644
--- a/core/lib/Drupal/Core/Entity/Plugin/Validation/Constraint/ValidReferenceConstraintValidator.php
+++ b/core/lib/Drupal/Core/Entity/Plugin/Validation/Constraint/ValidReferenceConstraintValidator.php
@@ -119,8 +119,7 @@ public function validate($value, Constraint $constraint) {
 
     // Don't try to validate pre-existing items.
     if ($target_ids) {
-      $entity = $value->getEntity();
-      if (!$entity->isNew()) {
+      if ($value->getParent() && ($entity = $value->getEntity()) && !$entity->isNew()) {
         $existing_entity = $this->entityTypeManager->getStorage($entity->getEntityTypeId())->loadUnchanged($entity->id());
         $referenced_entities = $existing_entity->{$value->getFieldDefinition()->getName()}->referencedEntities();