diff --git a/core/modules/field/field.api.php b/core/modules/field/field.api.php
index 456e434..0493015 100644
--- a/core/modules/field/field.api.php
+++ b/core/modules/field/field.api.php
@@ -81,7 +81,7 @@ function hook_field_storage_config_update_forbid(\Drupal\field\FieldStorageConfi
     $allowed_values = $field_storage->getSetting('allowed_values');
     $prior_allowed_values = $prior_field_storage->getSetting('allowed_values');
     $lost_keys = array_keys(array_diff_key($prior_allowed_values,$allowed_values));
-    if (_options_values_in_use($field_storage->entity_type, $field_storage->getName(), $lost_keys)) {
+    if (_options_values_in_use($field_storage->getTargetEntityTypeId(), $field_storage->getName(), $lost_keys)) {
       throw new \Drupal\Core\Entity\Exception\FieldStorageDefinitionUpdateForbiddenException(t('A list field (@field_name) with existing data cannot have its keys changed.', array('@field_name' => $field_storage->getName())));
     }
   }
diff --git a/core/modules/field/src/Entity/FieldStorageConfig.php b/core/modules/field/src/Entity/FieldStorageConfig.php
index 5e1ca32..2144c04 100644
--- a/core/modules/field/src/Entity/FieldStorageConfig.php
+++ b/core/modules/field/src/Entity/FieldStorageConfig.php
@@ -71,7 +71,7 @@ class FieldStorageConfig extends ConfigEntityBase implements FieldStorageConfigI
    *
    * @var string
    */
-  public $entity_type;
+  protected $entity_type;
 
   /**
    * The field type.
@@ -391,7 +391,8 @@ public static function preDelete(EntityStorageInterface $storage, array $field_s
     foreach ($field_storages as $field_storage) {
       if (!$field_storage->deleted) {
         foreach ($field_storage->getBundles() as $bundle) {
-          $field_ids[] = "{$field_storage->entity_type}.$bundle.{$field_storage->field_name}";
+          $entity_type = $field_storage->getTargetEntityTypeId();
+          $field_ids[] = "{$entity_type}.$bundle.{$field_storage->field_name}";
         }
       }
     }
diff --git a/core/modules/field_ui/src/FieldStorageConfigListBuilder.php b/core/modules/field_ui/src/FieldStorageConfigListBuilder.php
index 20d74b0..97403c5 100644
--- a/core/modules/field_ui/src/FieldStorageConfigListBuilder.php
+++ b/core/modules/field_ui/src/FieldStorageConfigListBuilder.php
@@ -111,11 +111,12 @@ public function buildRow(EntityInterface $field_storage) {
 
     $usage = array();
     foreach ($field_storage->getBundles() as $bundle) {
-      if ($route_info = FieldUI::getOverviewRouteInfo($field_storage->entity_type, $bundle)) {
-        $usage[] = \Drupal::l($this->bundles[$field_storage->entity_type][$bundle]['label'], $route_info);
+      $entity_type_id = $field_storage->getEntityTypeId();
+      if ($route_info = FieldUI::getOverviewRouteInfo($entity_type_id, $bundle)) {
+        $usage[] = \Drupal::l($this->bundles[$entity_type_id][$bundle]['label'], $route_info);
       }
       else {
-        $usage[] = $this->bundles[$field_storage->entity_type][$bundle]['label'];
+        $usage[] = $this->bundles[$entity_type_id][$bundle]['label'];
       }
     }
     $usage_escaped = '';
diff --git a/core/modules/file/file.views.inc b/core/modules/file/file.views.inc
index ee523b7..308812c 100644
--- a/core/modules/file/file.views.inc
+++ b/core/modules/file/file.views.inc
@@ -37,7 +37,7 @@ function file_field_views_data(FieldStorageConfigInterface $field_storage) {
  * Views integration to provide reverse relationships on file fields.
  */
 function file_field_views_data_views_data_alter(array &$data, FieldStorageConfigInterface $field_storage) {
-  $entity_type_id = $field_storage->entity_type;
+  $entity_type_id = $field_storage->getEntityTypeId();
   $entity_manager = \Drupal::entityManager();
   $entity_type = $entity_manager->getDefinition($entity_type_id);
   $field_name = $field_storage->getName();
diff --git a/core/modules/views/views.api.php b/core/modules/views/views.api.php
index a0d27ca..78ae8e0 100644
--- a/core/modules/views/views.api.php
+++ b/core/modules/views/views.api.php
@@ -478,7 +478,7 @@ function hook_field_views_data(\Drupal\field\FieldStorageConfigInterface $field_
  * @see hook_field_views_data_views_data_alter()
  */
 function hook_field_views_data_alter(array &$data, \Drupal\field\FieldStorageConfigInterface $field_storage) {
-  $entity_type_id = $field_storage->entity_type;
+  $entity_type_id = $field_storage->getEntityTypeId();
   $field_name = $field_storage->getName();
   $entity_type = \Drupal::entityManager()->getDefinition($entity_type_id);
   $pseudo_field_name = 'reverse_' . $field_name . '_' . $entity_type_id;