diff --git a/core/lib/Drupal/Core/Entity/ContentEntityBase.php b/core/lib/Drupal/Core/Entity/ContentEntityBase.php
index 82fbe7a..ed15979 100644
--- a/core/lib/Drupal/Core/Entity/ContentEntityBase.php
+++ b/core/lib/Drupal/Core/Entity/ContentEntityBase.php
@@ -433,9 +433,7 @@ public function set($property_name, $value, $notify = TRUE) {
     $this->get($property_name)->setValue($value, FALSE);
 
     if ($property_name == 'langcode') {
-      // Avoid using unset as this unnecessarily triggers magic methods later
-      // on.
-      $this->language = NULL;
+      $this->onChange($property_name);
     }
   }
 
diff --git a/core/modules/field/field.multilingual.inc b/core/modules/field/field.multilingual.inc
index 01c1af8..2ea2bf1 100644
--- a/core/modules/field/field.multilingual.inc
+++ b/core/modules/field/field.multilingual.inc
@@ -21,11 +21,11 @@
  * @endcode
  * Every field can hold a single or multiple value for each language code
  * belonging to the available language codes set:
- * - For untranslatable fields this set only contains Language::LANGCODE_NOT_SPECIFIED.
+ * - For untranslatable fields this set is only Language::LANGCODE_DEFAULT.
  * - For translatable fields this set can contain any language code. By default
  *   it is the list returned by field_content_languages(), which contains all
- *   installed languages with the addition of Language::LANGCODE_NOT_SPECIFIED. This
- *   default can be altered by modules implementing
+ *   installed languages with the addition of Language::LANGCODE_NOT_SPECIFIED.
+ *   This default can be altered by modules implementing
  *   hook_field_available_languages_alter().
  *
  * The available language codes for a particular field are returned by
@@ -69,10 +69,10 @@
  * Collects the available language codes for the given entity type and field.
  *
  * If the given field has language support enabled, an array of available
- * language codes will be returned, otherwise only Language::LANGCODE_NOT_SPECIFIED will
- * be returned. Since the default value for a 'translatable' entity property is
- * FALSE, we ensure that only entities that are able to handle translations
- * actually get translatable fields.
+ * language codes will be returned, otherwise only Language::LANGCODE_DEFAULT
+ * will be returned. Since the default value for a 'translatable' entity
+ * property is FALSE, we ensure that only entities that are able to handle
+ * translations actually get translatable fields.
  *
  * @param $entity_type
  *   The type of the entity the field is attached to, e.g. 'node' or 'user'.
@@ -92,8 +92,7 @@ function field_available_languages($entity_type, FieldInterface $field) {
 
   if (!isset($field_langcodes[$entity_type][$field_name])) {
     // If the field has language support enabled we retrieve an (alterable) list
-    // of enabled languages, otherwise we return just
-    // Language::LANGCODE_DEFAULT.
+    // of enabled languages, otherwise we return Language::LANGCODE_DEFAULT.
     if (field_is_translatable($entity_type, $field)) {
       $langcodes = field_content_languages();
       // Let other modules alter the available languages.
diff --git a/core/modules/field/lib/Drupal/field/Tests/TranslationTest.php b/core/modules/field/lib/Drupal/field/Tests/TranslationTest.php
index de2dd94..5b370a0 100644
--- a/core/modules/field/lib/Drupal/field/Tests/TranslationTest.php
+++ b/core/modules/field/lib/Drupal/field/Tests/TranslationTest.php
@@ -142,7 +142,7 @@ function testFieldAvailableLanguages() {
     $this->field->translatable = FALSE;
     $this->field->save();
     $available_langcodes = field_available_languages($this->entity_type, $this->field);
-    $this->assertTrue(count($available_langcodes) == 1 && $available_langcodes[0] === Language::LANGCODE_NOT_SPECIFIED, 'For untranslatable fields only Language::LANGCODE_NOT_SPECIFIED is available.');
+    $this->assertTrue(count($available_langcodes) == 1 && $available_langcodes[0] === Language::LANGCODE_DEFAULT, 'For untranslatable fields only Language::LANGCODE_NOT_SPECIFIED is available.');
   }
 
   /**