diff -u b/core/lib/Drupal/Core/Entity/ContentEntityBase.php b/core/lib/Drupal/Core/Entity/ContentEntityBase.php
--- b/core/lib/Drupal/Core/Entity/ContentEntityBase.php
+++ b/core/lib/Drupal/Core/Entity/ContentEntityBase.php
@@ -469,7 +469,7 @@
 
         // TODO remove this check after https://www.drupal.org/node/2828133
         // gets in.
-        if (!$serialize_fields_with_embedded_entities[$name]->isTranslatable() && ($langcode != LanguageInterface::LANGCODE_DEFAULT)) {
+        if (isset($serialize_fields_with_embedded_entities[$name]) && !$serialize_fields_with_embedded_entities[$name]->isTranslatable() && ($langcode != LanguageInterface::LANGCODE_DEFAULT)) {
           continue;
         }