diff --git a/core/config/schema/core.entity.schema.yml b/core/config/schema/core.entity.schema.yml
index 07e4714..60c4635 100644
--- a/core/config/schema/core.entity.schema.yml
+++ b/core/config/schema/core.entity.schema.yml
@@ -70,6 +70,9 @@ core.entity_view_display.*.*.*:
           settings:
             type: field.formatter.settings.[%parent.type]
             label: 'Settings'
+          settings_langcode:
+            type: string
+            label: 'Language code for settings'
           third_party_settings:
              type: sequence
              label: 'Third party settings'
@@ -123,6 +126,9 @@ core.entity_form_display.*.*.*:
             label: 'Third party settings'
             sequence:
               type: field.widget.third_party.[%key]
+          settings_langcode:
+            type: string
+            label: 'Language code for settings'
     hidden:
       type: sequence
       label: 'Hidden'
diff --git a/core/lib/Drupal/Core/Entity/EntityDisplayBase.php b/core/lib/Drupal/Core/Entity/EntityDisplayBase.php
index 3a59e01..8db6163 100644
--- a/core/lib/Drupal/Core/Entity/EntityDisplayBase.php
+++ b/core/lib/Drupal/Core/Entity/EntityDisplayBase.php
@@ -346,8 +346,13 @@ public function setComponent($name, array $options = array()) {
       $options = $this->pluginManager->prepareConfiguration($field_definition->getType(), $options);
     }
 
-    // Ensure we always have an empty settings and array.
-    $options += ['settings' => [], 'third_party_settings' => []];
+    // Ensure we always have an empty settings, third_party_settings, and
+    // settings_langcode if not provided.
+    $options += [
+      'settings' => [],
+      'third_party_settings' => [],
+      'settings_langcode' => NULL,
+    ];
 
     $this->content[$name] = $options;
     unset($this->hidden[$name]);
diff --git a/core/lib/Drupal/Core/Field/FormatterBase.php b/core/lib/Drupal/Core/Field/FormatterBase.php
index 41f8701..7b9bdce 100644
--- a/core/lib/Drupal/Core/Field/FormatterBase.php
+++ b/core/lib/Drupal/Core/Field/FormatterBase.php
@@ -32,6 +32,13 @@
   protected $settings;
 
   /**
+   * The language code for the formatter settings.
+   *
+   * @var string
+   */
+  protected $settingsLangcode;
+
+  /**
    * The label display setting.
    *
    * @var string
diff --git a/core/lib/Drupal/Core/Field/FormatterPluginManager.php b/core/lib/Drupal/Core/Field/FormatterPluginManager.php
index d100add..d29d101 100644
--- a/core/lib/Drupal/Core/Field/FormatterPluginManager.php
+++ b/core/lib/Drupal/Core/Field/FormatterPluginManager.php
@@ -61,8 +61,10 @@ public function createInstance($plugin_id, array $configuration = array()) {
     $plugin_definition = $this->getDefinition($plugin_id);
     $plugin_class = DefaultFactory::getPluginClass($plugin_id, $plugin_definition);
 
-    // @todo Not sure we need to keep that, there should always be a settings_langcode set ?
-    $configuration += ['settings_langcode' => NULL];
+    // @todo TEST CODE; REMOVE BEFORE COMMIT
+    if (!array_key_exists('settings_langcode', $configuration)) {
+      throw new \Exception('$configuration[settings_langcode] is missing in ' . $plugin_class);
+    }
 
     // @todo This is copied from \Drupal\Core\Plugin\Factory\ContainerFactory.
     //   Find a way to restore sanity to
@@ -155,6 +157,7 @@ public function prepareConfiguration($field_type, array $configuration) {
       'label' => 'above',
       'settings' => array(),
       'third_party_settings' => array(),
+      'settings_langcode' => NULL,
     );
     // If no formatter is specified, use the default formatter.
     if (!isset($configuration['type'])) {
diff --git a/core/modules/aggregator/config/install/core.entity_view_display.aggregator_feed.aggregator_feed.default.yml b/core/modules/aggregator/config/install/core.entity_view_display.aggregator_feed.aggregator_feed.default.yml
index 58e360f..5e7c967 100644
--- a/core/modules/aggregator/config/install/core.entity_view_display.aggregator_feed.aggregator_feed.default.yml
+++ b/core/modules/aggregator/config/install/core.entity_view_display.aggregator_feed.aggregator_feed.default.yml
@@ -11,6 +11,7 @@ content:
     weight: 1
     settings: {  }
     third_party_settings: {  }
+    settings_langcode: null
     label: inline
   image:
     weight: 2
@@ -21,6 +22,7 @@ content:
     weight: 4
     settings: {  }
     third_party_settings: {  }
+    settings_langcode: null
     label: inline
   feed_icon:
     weight: 5