diff --git a/core/lib/Drupal/Core/Entity/DatabaseStorageControllerNG.php b/core/lib/Drupal/Core/Entity/DatabaseStorageControllerNG.php
index 3597d5a..bb0cf4c 100644
--- a/core/lib/Drupal/Core/Entity/DatabaseStorageControllerNG.php
+++ b/core/lib/Drupal/Core/Entity/DatabaseStorageControllerNG.php
@@ -560,7 +560,7 @@ protected function mapToRevisionStorageRecord(EntityInterface $entity) {
    *   The record to store.
    */
   protected function mapToDataStorageRecord(EntityInterface $entity, $langcode) {
-    $default_langcode = $entity->getUntranslated()->language()->langcode;
+    $default_langcode = $entity->getUntranslated()->language()->id;
     // Don't use strict mode, this way there's no need to do checks here, as
     // non-translatable properties are replicated for each language.
     $translation = $entity->getTranslation($langcode);
diff --git a/core/lib/Drupal/Core/Entity/EntityNG.php b/core/lib/Drupal/Core/Entity/EntityNG.php
index 61a013f..a7bf102 100644
--- a/core/lib/Drupal/Core/Entity/EntityNG.php
+++ b/core/lib/Drupal/Core/Entity/EntityNG.php
@@ -156,7 +156,7 @@ public function __construct(array $values, $entity_type, $bundle = FALSE, $trans
     $data = array('status' => self::$TRANSLATION_EXISTING);
     $this->translations[Language::LANGCODE_DEFAULT] = $data;
     if ($translations) {
-      $default_langcode = $this->language()->langcode;
+      $default_langcode = $this->language()->id;
       foreach ($translations as $langcode) {
         if ($langcode != $default_langcode && $langcode != Language::LANGCODE_DEFAULT) {
           $this->translations[$langcode] = $data;
diff --git a/core/modules/field/field.module b/core/modules/field/field.module
index 0dca8b9..ad11478 100644
--- a/core/modules/field/field.module
+++ b/core/modules/field/field.module
@@ -235,7 +235,7 @@ function field_system_info_alter(&$info, $file, $type) {
 function field_entity_create(EntityInterface $entity) {
   $info = $entity->entityInfo();
   if (!empty($info['fieldable'])) {
-    field_populate_default_values($entity, $entity->language()->langcode);
+    field_populate_default_values($entity, $entity->language()->id);
   }
 }
 
diff --git a/core/modules/field/lib/Drupal/field/Tests/TranslationWebTest.php b/core/modules/field/lib/Drupal/field/Tests/TranslationWebTest.php
index c65de42..df93f12 100644
--- a/core/modules/field/lib/Drupal/field/Tests/TranslationWebTest.php
+++ b/core/modules/field/lib/Drupal/field/Tests/TranslationWebTest.php
@@ -117,7 +117,7 @@ function testFieldFormTranslationRevisions() {
     $entity->save();
 
     // Create a new revision.
-    $langcode = $entity->language()->langcode;
+    $langcode = $entity->language()->id;
     $edit = array(
       'user_id' => 1,
       'name' => $this->randomName(),
diff --git a/core/modules/system/lib/Drupal/system/Tests/Entity/EntityTranslationTest.php b/core/modules/system/lib/Drupal/system/Tests/Entity/EntityTranslationTest.php
index 95d9f89..6bd3228 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Entity/EntityTranslationTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Entity/EntityTranslationTest.php
@@ -354,8 +354,8 @@ function testEntityTranslationAPI() {
     $translation = $entity->addTranslation($langcode);
     $this->assertNotEqual($entity, $translation, 'The entity and the translation object differ from one another.');
     $this->assertTrue($entity->hasTranslation($langcode), 'The new translation exists.');
-    $this->assertEqual($translation->language()->langcode, $langcode, 'The translation language matches the specified one.');
-    $this->assertEqual($translation->getUntranslated()->language()->langcode, $default_langcode, 'The original language can still be retrieved.');
+    $this->assertEqual($translation->language()->id, $langcode, 'The translation language matches the specified one.');
+    $this->assertEqual($translation->getUntranslated()->language()->id, $default_langcode, 'The original language can still be retrieved.');
     $translation->name->value = $name_translated;
     $this->assertEqual($entity->name->value, $name, 'The original name is retained after setting a translated value.');
     $entity->name->value = $name;
@@ -369,16 +369,16 @@ function testEntityTranslationAPI() {
 
     // Check that after loading an entity the language is the default one.
     $entity = $this->reloadEntity($entity);
-    $this->assertEqual($entity->language()->langcode, $default_langcode, 'The loaded entity is the original one.');
+    $this->assertEqual($entity->language()->id, $default_langcode, 'The loaded entity is the original one.');
 
     // Add another translation and check that everything works as expected. A
     // new translation object can be obtained also by just specifying a valid
     // language.
     $langcode2 = $this->langcodes[2];
     $translation = $entity->getTranslation($langcode2);
-    $value = $entity != $translation && $translation->language()->langcode == $langcode2 && $entity->hasTranslation($langcode2);
+    $value = $entity != $translation && $translation->language()->id == $langcode2 && $entity->hasTranslation($langcode2);
     $this->assertTrue($value, 'A new translation object can be obtained also by specifying a valid language.');
-    $this->assertEqual($entity->language()->langcode, $default_langcode, 'The original language has been preserved.');
+    $this->assertEqual($entity->language()->id, $default_langcode, 'The original language has been preserved.');
     $translation->save();
     $hooks = $this->getHooksInfo();
     $this->assertEqual($hooks['entity_translation_insert'], $langcode2, 'The generic entity translation insertion hook has fired.');
diff --git a/core/modules/system/tests/modules/entity_test/entity_test.module b/core/modules/system/tests/modules/entity_test/entity_test.module
index 03dc4dc..264787e 100644
--- a/core/modules/system/tests/modules/entity_test/entity_test.module
+++ b/core/modules/system/tests/modules/entity_test/entity_test.module
@@ -439,28 +439,28 @@ function entity_test_entity_operation_alter(array &$operations, EntityInterface
  * Implements hook_entity_translation_insert().
  */
 function entity_test_entity_translation_insert(EntityInterface $translation) {
-  _entity_test_record_hooks('entity_translation_insert', $translation->language()->langcode);
+  _entity_test_record_hooks('entity_translation_insert', $translation->language()->id);
 }
 
 /**
  * Implements hook_entity_translation_delete().
  */
 function entity_test_entity_translation_delete(EntityInterface $translation) {
-  _entity_test_record_hooks('entity_translation_delete', $translation->language()->langcode);
+  _entity_test_record_hooks('entity_translation_delete', $translation->language()->id);
 }
 
 /**
  * Implements hook_ENTITY_TYPE_translation_insert().
  */
 function entity_test_entity_test_mul_translation_insert(EntityInterface $translation) {
-  _entity_test_record_hooks('entity_test_mul_translation_insert', $translation->language()->langcode);
+  _entity_test_record_hooks('entity_test_mul_translation_insert', $translation->language()->id);
 }
 
 /**
  * Implements hook_ENTITY_TYPE_translation_delete().
  */
 function entity_test_entity_test_mul_translation_delete(EntityInterface $translation) {
-  _entity_test_record_hooks('entity_test_mul_translation_delete', $translation->language()->langcode);
+  _entity_test_record_hooks('entity_test_mul_translation_delete', $translation->language()->id);
 }
 
 /**
diff --git a/core/modules/taxonomy/lib/Drupal/taxonomy/TermFormController.php b/core/modules/taxonomy/lib/Drupal/taxonomy/TermFormController.php
index 91b2586..4f4043a 100644
--- a/core/modules/taxonomy/lib/Drupal/taxonomy/TermFormController.php
+++ b/core/modules/taxonomy/lib/Drupal/taxonomy/TermFormController.php
@@ -47,7 +47,7 @@ public function form(array $form, array &$form_state) {
       '#type' => 'language_select',
       '#title' => t('Language'),
       '#languages' => Language::STATE_ALL,
-      '#default_value' => $term->getUntranslated()->language()->langcode,
+      '#default_value' => $term->getUntranslated()->language()->id,
       '#access' => !is_null($language_configuration['language_show']) && $language_configuration['language_show'],
     );