diff --git a/core/lib/Drupal/Core/Routing/CachedUrlGenerator.php b/core/lib/Drupal/Core/Routing/CachedUrlGenerator.php
index 5de0e67..9f0b960 100644
--- a/core/lib/Drupal/Core/Routing/CachedUrlGenerator.php
+++ b/core/lib/Drupal/Core/Routing/CachedUrlGenerator.php
@@ -90,7 +90,7 @@ public function __construct(UrlGeneratorInterface $url_generator, CacheBackendIn
   /**
    * Clears the caches of the URL generator.
    */
-  public function clear() {
+  public function clearCache() {
     $this->cachedUrls = array();
     $this->cache->delete($this->cacheKey);
   }
diff --git a/core/lib/Drupal/Core/Routing/UrlGenerator.php b/core/lib/Drupal/Core/Routing/UrlGenerator.php
index ac5d5c8..c45ab6e 100644
--- a/core/lib/Drupal/Core/Routing/UrlGenerator.php
+++ b/core/lib/Drupal/Core/Routing/UrlGenerator.php
@@ -370,4 +370,10 @@ protected function getRoute($name) {
     return $route;
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function clearCache() {
+    // Nothing to do in this class.
+  }
 }
diff --git a/core/lib/Drupal/Core/Routing/UrlGeneratorInterface.php b/core/lib/Drupal/Core/Routing/UrlGeneratorInterface.php
index 62fe1ef..e526474 100644
--- a/core/lib/Drupal/Core/Routing/UrlGeneratorInterface.php
+++ b/core/lib/Drupal/Core/Routing/UrlGeneratorInterface.php
@@ -199,4 +199,8 @@ public function setBasePath($path);
    */
   public function setScriptPath($path);
 
+  /**
+   * Clears the caches of the URL generator.
+   */
+  public function clearCache();
 }
diff --git a/core/modules/language/lib/Drupal/language/Tests/LanguageListTest.php b/core/modules/language/lib/Drupal/language/Tests/LanguageListTest.php
index 4870f57..46c39bf 100644
--- a/core/modules/language/lib/Drupal/language/Tests/LanguageListTest.php
+++ b/core/modules/language/lib/Drupal/language/Tests/LanguageListTest.php
@@ -46,7 +46,8 @@ function testLanguageList() {
     );
     $this->drupalPost('admin/config/regional/language/add', $edit, t('Add language'));
     $this->assertText('French', 'Language added successfully.');
-    $this->assertEqual($this->getUrl(), url('admin/config/regional/language', array('absolute' => TRUE)), 'Correct page redirection.');
+    // Check for correct page redirection.
+    $this->assertEqual($this->getUrl(), url('admin/config/regional/language', array('absolute' => TRUE)));
 
     // Add custom language.
     $langcode = 'xx';
@@ -58,7 +59,8 @@ function testLanguageList() {
       'direction' => '0',
     );
     $this->drupalPost('admin/config/regional/language/add', $edit, t('Add custom language'));
-    $this->assertEqual($this->getUrl(), url('admin/config/regional/language', array('absolute' => TRUE)), 'Correct page redirection.');
+    // Check for correct page redirection.
+    $this->assertEqual($this->getUrl(), url('admin/config/regional/language', array('absolute' => TRUE)));
     $this->assertRaw('"edit-languages-' . $langcode .'-weight"', 'Language code found.');
     $this->assertText(t($name), 'Test language added.');
 
@@ -71,12 +73,16 @@ function testLanguageList() {
       'site_default_language' => $langcode,
     );
     $this->drupalPost(NULL, $edit, t('Save configuration'));
+    // Clear cached urls in the local process too.
+    $this->container->get('url_generator')->clearCache();
     $this->assertNoOptionSelected('edit-site-default-language', 'en', 'Default language updated.');
-    $this->assertEqual($this->getUrl(), url($path, array('absolute' => TRUE)), 'Correct page redirection.');
+    // Check for correct page redirection.
+    $this->assertEqual($this->getUrl(), url($path, array('absolute' => TRUE)));
 
     // Ensure we can't delete the default language.
     $this->drupalGet('admin/config/regional/language/delete/' . $langcode);
-    $this->assertEqual($this->getUrl(), url('admin/config/regional/language', array('absolute' => TRUE)), 'Correct page redirection.');
+    // Check for correct page redirection.
+    $this->assertEqual($this->getUrl(), url('admin/config/regional/language', array('absolute' => TRUE)));
     $this->assertText(t('The default language cannot be deleted.'), 'Failed to delete the default language.');
 
     // Ensure 'Edit' link works.
@@ -89,13 +95,16 @@ function testLanguageList() {
     );
     $this->drupalPost('admin/config/regional/language/edit/' . $langcode, $edit, t('Save language'));
     $this->assertRaw($name, 'The language has been updated.');
-    $this->assertEqual($this->getUrl(), url('admin/config/regional/language', array('absolute' => TRUE)), 'Correct page redirection.');
+    // Check for correct page redirection.
+    $this->assertEqual($this->getUrl(), url('admin/config/regional/language', array('absolute' => TRUE)));
 
     // Change back the default language.
     $edit = array(
       'site_default_language' => 'en',
     );
     $this->drupalPost($path, $edit, t('Save configuration'));
+    // Clear cached urls in the local process too.
+    $this->container->get('url_generator')->clearCache();
     // Ensure 'delete' link works.
     $this->drupalGet('admin/config/regional/language');
     $this->clickLink(t('Delete'));
@@ -104,7 +113,8 @@ function testLanguageList() {
     $this->drupalGet('admin/config/regional/language/delete/' . $langcode);
     // First test the 'cancel' link.
     $this->clickLink(t('Cancel'));
-    $this->assertEqual($this->getUrl(), url('admin/config/regional/language', array('absolute' => TRUE)), 'Correct page redirection.');
+    // Check for correct page redirection.
+    $this->assertEqual($this->getUrl(), url('admin/config/regional/language', array('absolute' => TRUE)));
     $this->assertRaw($name, 'The language was not deleted.');
     // Delete the language for real. This a confirm form, we do not need any
     // fields changed.
@@ -112,7 +122,8 @@ function testLanguageList() {
     // We need raw here because %language and %langcode will add HTML.
     $t_args = array('%language' => $name, '%langcode' => $langcode);
     $this->assertRaw(t('The %language (%langcode) language has been removed.', $t_args), 'The test language has been removed.');
-    $this->assertEqual($this->getUrl(), url('admin/config/regional/language', array('absolute' => TRUE)), 'Correct page redirection.');
+    // Check for correct page redirection.
+    $this->assertEqual($this->getUrl(), url('admin/config/regional/language', array('absolute' => TRUE)));
     // Verify that language is no longer found.
     $this->drupalGet('admin/config/regional/language/delete/' . $langcode);
     $this->assertResponse(404, 'Language no longer found.');
@@ -121,6 +132,8 @@ function testLanguageList() {
     $languages = language_list();
     $language_count =  $this->container->get('state')->get('language_count') ?: 1;
     $this->assertEqual($language_count, count($languages), 'Language count is correct.');
+    // Clear cached urls in the local process too.
+    $this->container->get('url_generator')->clearCache();
     // Delete French.
     $this->drupalPost('admin/config/regional/language/delete/fr', array(), t('Delete'));
     // Get the count of languages.
@@ -129,7 +142,8 @@ function testLanguageList() {
     // We need raw here because %language and %langcode will add HTML.
     $t_args = array('%language' => 'French', '%langcode' => 'fr');
     $this->assertRaw(t('The %language (%langcode) language has been removed.', $t_args), 'Disabled language has been removed.');
-    $this->assertEqual($this->getUrl(), url('admin/config/regional/language', array('absolute' => TRUE)), 'Correct page redirection.');
+    // Check for correct page redirection.
+    $this->assertEqual($this->getUrl(), url('admin/config/regional/language', array('absolute' => TRUE)));
     // Verify that language is no longer found.
     $this->drupalGet('admin/config/regional/language/delete/fr');
     $this->assertResponse(404, 'Language no longer found.');
@@ -149,7 +163,10 @@ function testLanguageList() {
       'direction' => '0',
     );
     $this->drupalPost('admin/config/regional/language/add', $edit, t('Add custom language'));
-    $this->assertEqual($this->getUrl(), url('admin/config/regional/language', array('absolute' => TRUE)), 'Correct page redirection.');
+    // Clear cached urls in the local process too.
+    $this->container->get('url_generator')->clearCache();
+    // Check for correct page redirection.
+    $this->assertEqual($this->getUrl(), url('admin/config/regional/language', array('absolute' => TRUE)));
     $this->assertText($name, 'Name found.');
 
     // Check if we can change the default language.
@@ -161,8 +178,11 @@ function testLanguageList() {
       'site_default_language' => $langcode,
     );
     $this->drupalPost(NULL, $edit, t('Save configuration'));
+    // Clear cached urls in the local process too.
+    $this->container->get('url_generator')->clearCache();
     $this->assertNoOptionSelected('edit-site-default-language', 'en', 'Default language updated.');
-    $this->assertEqual($this->getUrl(), url($path, array('absolute' => TRUE)), 'Correct page redirection.');
+    // Check for correct page redirection.
+    $this->assertEqual($this->getUrl(), url($path, array('absolute' => TRUE)));
 
     $this->drupalPost('admin/config/regional/language/delete/en', array(), t('Delete'));
     // We need raw here because %language and %langcode will add HTML.
diff --git a/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
index 8d907ac..06dcef9 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/WebTestBase.php
@@ -3403,10 +3403,8 @@ protected function prepareRequestForGenerator($clean_urls = TRUE, $override_serv
     $request = Request::create($request_path, 'GET', array(), array(), array(), $server);
     $generator->setRequest($request);
 
-    // Ensure to clear some internal caches of the URL generator.
-    if ($generator instanceof CachedUrlGenerator) {
-      $generator->clear();
-    }
+    // Ensure any internal caches of the URL generator are cleared.
+    $generator->clearCache();
 
     return $request;
   }
diff --git a/core/modules/system/lib/Drupal/system/Form/RegionalForm.php b/core/modules/system/lib/Drupal/system/Form/RegionalForm.php
index 52f5db5..f47a104 100644
--- a/core/modules/system/lib/Drupal/system/Form/RegionalForm.php
+++ b/core/modules/system/lib/Drupal/system/Form/RegionalForm.php
@@ -166,9 +166,7 @@ public function submitForm(array &$form, array &$form_state) {
       ->set('timezone.user.default', $form_state['values']['user_default_timezone'])
       ->save();
 
-    if (method_exists($this->urlGenerator, 'clear')) {
-      $this->urlGenerator->clear();
-    }
+    $this->urlGenerator->clearCache();
 
     parent::submitForm($form, $form_state);
   }