diff -u b/core/modules/ckeditor/config/schema/ckeditor.schema.yml b/core/modules/ckeditor/config/schema/ckeditor.schema.yml
--- b/core/modules/ckeditor/config/schema/ckeditor.schema.yml
+++ b/core/modules/ckeditor/config/schema/ckeditor.schema.yml
@@ -45,4 +44,0 @@
-# Plugin \Drupal\ckeditor\Plugin\ckeditor\plugin\Language
-ckeditor.plugin.language:
-  type: string
-  label: 'Language list type'
diff -u b/core/modules/ckeditor/src/Plugin/CKEditorPlugin/Language.php b/core/modules/ckeditor/src/Plugin/CKEditorPlugin/Language.php
--- b/core/modules/ckeditor/src/Plugin/CKEditorPlugin/Language.php
+++ b/core/modules/ckeditor/src/Plugin/CKEditorPlugin/Language.php
@@ -54,8 +54,13 @@
    */
   public function getConfig(Editor $editor) {
     $language_list = array();
+    $config = array('list_type' => 'un');
     $settings = $editor->getSettings();
-    $predefined_languages = ($settings['plugins']['language']['list_type'] == 'all') ?
+    if (isset($settings['plugins']['language'])) {
+      $config = $settings['plugins']['language'];
+    }
+
+    $predefined_languages = ($config['list_type'] == 'all') ?
       LanguageManager::getStandardLanguageList() :
       LanguageManager::getUnitedNationsLanguageList();
 
@@ -94,7 +99,11 @@
    * {@inheritdoc}
    */
   public function settingsForm(array $form, FormStateInterface $form_state, Editor $editor) {
+    $config = array('list_type' => 'un');
     $settings = $editor->getSettings();
+    if (isset($settings['plugins']['language'])) {
+      $config = $settings['plugins']['language'];
+    }
 
     $predefined_languages = LanguageManager::getStandardLanguageList();
     $form['list_type'] = array(
@@ -105,7 +114,7 @@
         'un' => t('United Nations subset'),
         'all' => t('All @count languages', array('@count' => sizeof($predefined_languages))),
       ),
-      '#default_value' => $settings['plugins']['language']['list_type'],
+      '#default_value' => $config['list_type'],
       '#description' => t('The list of languages to show in the language dropdown. The basic list will only show the <a href="@url">six official languages of the UN</a>. The extended list will show all @count languages that are available in Drupal.', array(
         '@url' => Url::fromUri('http://www.un.org/en/aboutun/languages.shtml/'),
         '@count' => sizeof($predefined_languages),
diff -u b/core/modules/ckeditor/tests/src/Unit/Plugin/CKEditorPlugin/LanguageTest.php b/core/modules/ckeditor/tests/src/Unit/Plugin/CKEditorPlugin/LanguageTest.php
--- b/core/modules/ckeditor/tests/src/Unit/Plugin/CKEditorPlugin/LanguageTest.php
+++ b/core/modules/ckeditor/tests/src/Unit/Plugin/CKEditorPlugin/LanguageTest.php
@@ -7,8 +7,6 @@
 
 /**
  * @coversDefaultClass \Drupal\ckeditor\Plugin\CKEditorPlugin\Language
- *
- * @group Foo
  */
 class LanguageTest extends UnitTestCase {
 
only in patch2:
unchanged:
--- a/core/modules/ckeditor/src/Tests/CKEditorAdminTest.php
+++ b/core/modules/ckeditor/src/Tests/CKEditorAdminTest.php
@@ -125,11 +125,11 @@ function testExistingFormat() {
 
     // Ensure an Editor object exists now, with the proper settings.
     $expected_settings = $expected_default_settings;
+    $expected_settings['plugins']['language']['list_type'] = 'un';
     $expected_settings['plugins']['stylescombo']['styles'] = '';
     $editor = entity_load('editor', 'filtered_html');
     $this->assertTrue($editor instanceof Editor, 'An Editor config entity exists now.');
     $this->assertIdentical($expected_settings, $editor->getSettings(), 'The Editor config entity has the correct settings.');
-
     // Configure the Styles plugin, and ensure the updated settings are saved.
     $this->drupalGet('admin/config/content/formats/manage/filtered_html');
     $edit = array(
@@ -241,6 +241,7 @@ function testNewFormat() {
 
     // Ensure an Editor object exists now, with the proper settings.
     $expected_settings = $default_settings;
+    $expected_settings['plugins']['language']['list_type'] = 'un';
     $expected_settings['plugins']['stylescombo']['styles'] = '';
     $editor = entity_load('editor', 'amazing_format');
     $this->assertTrue($editor instanceof Editor, 'An Editor config entity exists now.');