reverted:
--- b/core/modules/hal/src/Tests/NormalizeTest.php
+++ a/core/modules/hal/src/Tests/NormalizeTest.php
@@ -79,13 +79,13 @@
         ),
         $relation_uri => array(
           array(
+            'href' => $this->getEntityUri($target_entity_de),
+            'lang' => 'de',
+          ),
+          array(
             'href' => $this->getEntityUri($target_entity_en),
             'lang' => 'en',
           ),
-          array(
-            'href' => $this->getEntityUri($target_entity_de),
-            'lang' => 'de',
-          ),
         ),
       ),
       '_embedded' => array(
@@ -93,7 +93,7 @@
           array(
             '_links' => array(
               'self' => array(
+                'href' => $this->getEntityUri($target_entity_de),
-                'href' => $this->getEntityUri($target_entity_en),
               ),
               'type' => array(
                 'href' => $type_uri,
@@ -101,15 +101,15 @@
             ),
             'uuid' => array(
               array(
+                'value' => $target_entity_de->uuid(),
-                'value' => $target_entity_en->uuid(),
               ),
             ),
+            'lang' => 'de',
-            'lang' => 'en',
           ),
           array(
             '_links' => array(
               'self' => array(
+                'href' => $this->getEntityUri($target_entity_en),
-                'href' => $this->getEntityUri($target_entity_de),
               ),
               'type' => array(
                 'href' => $type_uri,
@@ -117,10 +117,10 @@
             ),
             'uuid' => array(
               array(
+                'value' => $target_entity_en->uuid(),
-                'value' => $target_entity_de->uuid(),
               ),
             ),
+            'lang' => 'en',
-            'lang' => 'de',
           ),
         ),
       ),
@@ -136,13 +136,13 @@
       ),
       'name' => array(
         array(
+          'value' => $values['name'],
+          'lang' => 'de',
+        ),
+        array(
           'value' => $translation_values['name'],
           'lang' => 'en',
         ),
-        array(
-          'value' => $values['name'],
-          'lang' => 'de',
-        ),
       ),
       'field_test_text' => array(
         array(
reverted:
--- b/core/modules/language/src/ConfigurableLanguageManager.php
+++ a/core/modules/language/src/ConfigurableLanguageManager.php
@@ -353,11 +353,10 @@
     if (reset($locked_languages)->getWeight() <= $max_weight) {
       foreach ($locked_languages as $language) {
         // Update system languages weight.
+        $max_weight++;
+        ConfigurableLanguage::load($language->getId())
+          ->setWeight($max_weight)
+          ->save();
-        if ($language = ConfigurableLanguage::load($language->getId())) {
-          $max_weight++;
-          $language->setWeight($max_weight)
-            ->save();
-        }
       }
     }
   }
diff -u b/core/modules/language/src/Entity/ConfigurableLanguage.php b/core/modules/language/src/Entity/ConfigurableLanguage.php
--- b/core/modules/language/src/Entity/ConfigurableLanguage.php
+++ b/core/modules/language/src/Entity/ConfigurableLanguage.php
@@ -121,18 +121,14 @@
     // For the uncommon case of custom languages the label should be given in
     // English.
     $this->langcode = 'en';
+
     // When adding a new language the weight shouldn't be zero to avoid a
     // reordering of the languages list when their names change i.e. interface
     // translation.
-    // Fetch all configurable languages ordered by weight.
-    $languages = \Drupal::languageManager()->getLanguages($this::STATE_CONFIGURABLE);
-    // Retrieve the last.
-    $last_language = end($languages);
-    // When adding the first Configurable language leave the weight by default.
-    // This happens when you are installing language module.
-    if ($this->isNew() && $last_language->getId() != $this->getId()) {
-      // The newly created language will have the weight of the heaviest
-      // language +1.
+    if ($this->id != 'en' && $this->isNew() && !$this->isLocked() && $this->getWeight() == 0) {
+      // Fetch all configurable languages ordered by weight.
+      $languages = \Drupal::languageManager()->getLanguages($this::STATE_CONFIGURABLE);
+      $last_language = end($languages);
       $this->setWeight($last_language->getWeight() + 1);
     }
   }
@@ -145,7 +141,7 @@
 
     $language_manager = \Drupal::languageManager();
     $language_manager->reset();
-    if (!$this->isLocked() && $language_manager instanceof ConfigurableLanguageManagerInterface) {
+    if (!$this->isLocked() && $language_manager instanceof ConfigurableLanguageManagerInterface && !$this->isSyncing()) {
       $language_manager->updateLockedLanguageWeights();
     }
 
@@ -187,7 +183,8 @@
     parent::postDelete($storage, $entities);
     $language_manager = \Drupal::languageManager();
     $language_manager->reset();
-    if ($language_manager instanceof ConfigurableLanguageManagerInterface) {
+    $entity = reset($entities);
+    if ($language_manager instanceof ConfigurableLanguageManagerInterface && !$entity->isUninstalling() && !$entity->isSyncing()) {
       $language_manager->updateLockedLanguageWeights();
     }
     // If after deleting this language the site will become monolingual, we need
only in patch2:
unchanged:
--- a/core/modules/ckeditor/src/Tests/CKEditorTest.php
+++ b/core/modules/ckeditor/src/Tests/CKEditorTest.php
@@ -384,6 +384,7 @@ function testLanguages() {
    */
   function testJSTranslation() {
     $this->enableModules(array('language', 'locale'));
+    $this->installConfig(['language']);
     $this->installSchema('locale', 'locales_source');
     $this->installSchema('locale', 'locales_location');
     $this->installSchema('locale', 'locales_target');
only in patch2:
unchanged:
--- a/core/modules/config/src/Tests/ConfigLanguageOverrideTest.php
+++ b/core/modules/config/src/Tests/ConfigLanguageOverrideTest.php
@@ -29,7 +29,7 @@ class ConfigLanguageOverrideTest extends KernelTestBase {
    */
   protected function setUp() {
     parent::setUp();
-    $this->installConfig(array('config_test'));
+    $this->installConfig(array('config_test', 'language'));
   }
 
   /**
only in patch2:
unchanged:
--- a/core/modules/language/src/Tests/EntityDefaultLanguageTest.php
+++ b/core/modules/language/src/Tests/EntityDefaultLanguageTest.php
@@ -30,7 +30,7 @@ class EntityDefaultLanguageTest extends KernelTestBase {
    */
   public function setUp() {
     parent::setUp();
-
+    $this->installConfig(['language']);
     $this->installEntitySchema('user');
 
     // Activate Spanish language, so there are two languages activated.
only in patch2:
unchanged:
--- a/core/modules/language/src/Tests/LanguageConfigOverrideInstallTest.php
+++ b/core/modules/language/src/Tests/LanguageConfigOverrideInstallTest.php
@@ -24,6 +24,14 @@ class LanguageConfigOverrideInstallTest extends KernelTestBase {
   public static $modules = array('language', 'config_events_test');
 
   /**
+   * {@inheritdoc}
+   */
+  public function setUp() {
+    parent::setUp();
+    $this->installConfig(['language']);
+  }
+
+  /**
    * Tests the configuration events are not fired during install of overrides.
    */
   public function testLanguageConfigOverrideInstall() {
only in patch2:
unchanged:
--- a/core/modules/locale/src/Tests/LocaleConfigManagerTest.php
+++ b/core/modules/locale/src/Tests/LocaleConfigManagerTest.php
@@ -29,7 +29,7 @@ class LocaleConfigManagerTest extends KernelTestBase {
    */
   public function testHasTranslation() {
     $this->installSchema('locale', array('locales_location'));
-    $this->installConfig(array('locale_test'));
+    $this->installConfig(array('locale_test', 'language'));
     $locale_config_manager = \Drupal::service('locale.config.typed');
 
     $language = ConfigurableLanguage::createFromLangcode('de');
only in patch2:
unchanged:
--- a/core/modules/locale/src/Tests/LocaleConfigSubscriberTest.php
+++ b/core/modules/locale/src/Tests/LocaleConfigSubscriberTest.php
@@ -72,7 +72,7 @@ protected function setUp() {
 
     $this->installSchema('locale', ['locales_source', 'locales_target', 'locales_location']);
 
-    $this->installConfig(['locale_test']);
+    $this->installConfig(['locale_test', 'language']);
     ConfigurableLanguage::createFromLangcode($this->langcode)->save();
   }