diff --git a/core/lib/Drupal/Core/Language/LanguageManager.php b/core/lib/Drupal/Core/Language/LanguageManager.php
index d7b88d0..4d86ea3 100644
--- a/core/lib/Drupal/Core/Language/LanguageManager.php
+++ b/core/lib/Drupal/Core/Language/LanguageManager.php
@@ -338,7 +338,7 @@ public static function getStandardLanguageList() {
    *
    * @see \Drupal\language\ConfigurableLanguageManager::setConfigOverrideLanguage()
    */
-  public function setConfigOverrideLanguage(Language $language) {
+  public function setConfigOverrideLanguage(Language $language = NULL) {
     return $this;
   }
 
diff --git a/core/lib/Drupal/Core/Language/LanguageManagerInterface.php b/core/lib/Drupal/Core/Language/LanguageManagerInterface.php
index 2589790..e638edf 100644
--- a/core/lib/Drupal/Core/Language/LanguageManagerInterface.php
+++ b/core/lib/Drupal/Core/Language/LanguageManagerInterface.php
@@ -176,7 +176,7 @@ function getLanguageSwitchLinks($type, $path);
    *
    * @return $this
    */
-  public function setConfigOverrideLanguage(Language $language);
+  public function setConfigOverrideLanguage(Language $language = NULL);
 
   /**
    * Gets the current configuration override language.
diff --git a/core/modules/language/lib/Drupal/language/ConfigurableLanguageManager.php b/core/modules/language/lib/Drupal/language/ConfigurableLanguageManager.php
index ab834be..5cd3d8e 100644
--- a/core/modules/language/lib/Drupal/language/ConfigurableLanguageManager.php
+++ b/core/modules/language/lib/Drupal/language/ConfigurableLanguageManager.php
@@ -389,7 +389,7 @@ public function getLanguageSwitchLinks($type, $path) {
   /**
    * {@inheritdoc}
    */
-  public function setConfigOverrideLanguage(Language $language) {
+  public function setConfigOverrideLanguage(Language $language = NULL) {
     $this->configFactoryOverride->setLanguage($language);
     return $this;
   }