diff --git a/core/lib/Drupal/Core/Field/EntityReferenceFieldItemList.php b/core/lib/Drupal/Core/Field/EntityReferenceFieldItemList.php
index aba08ed..de57c9b 100644
--- a/core/lib/Drupal/Core/Field/EntityReferenceFieldItemList.php
+++ b/core/lib/Drupal/Core/Field/EntityReferenceFieldItemList.php
@@ -16,6 +16,10 @@ class EntityReferenceFieldItemList extends FieldItemList implements EntityRefere
    * {@inheritdoc}
    */
   public function referencedEntities() {
+    if (!isset($this->list)) {
+      return array();
+    }
+
     // Get a list of items having non-empty target ids.
     $list = array_filter($this->list, function($item) {
       return (bool) $item->target_id;
diff --git a/core/modules/file/lib/Drupal/file/Plugin/Field/FieldType/FileFieldItemList.php b/core/modules/file/lib/Drupal/file/Plugin/Field/FieldType/FileFieldItemList.php
index d46f7f8..43dbefa 100644
--- a/core/modules/file/lib/Drupal/file/Plugin/Field/FieldType/FileFieldItemList.php
+++ b/core/modules/file/lib/Drupal/file/Plugin/Field/FieldType/FileFieldItemList.php
@@ -72,8 +72,8 @@ public function update() {
     }
 
     // Add new usage entries for newly added files.
-    foreach ($files as $fid => $file) {
-      if (!in_array($fid, $original_fids)) {
+    foreach ($files as $file) {
+      if (!in_array($file->id(), $original_fids)) {
         \Drupal::service('file.usage')->add($file, 'file', $entity->getEntityTypeId(), $entity->id());
       }
     }