diff --git a/core/modules/system/src/Form/ModulesListConfirmForm.php b/core/modules/system/src/Form/ModulesListConfirmForm.php
index df7dfef..c04a030 100644
--- a/core/modules/system/src/Form/ModulesListConfirmForm.php
+++ b/core/modules/system/src/Form/ModulesListConfirmForm.php
@@ -147,7 +147,6 @@ public function submitForm(array &$form, FormStateInterface $form_state) {
     // Gets module list after install process, flushes caches and displays a
     // message if there are changes.
     if ($before != $this->moduleHandler->getModuleList()) {
-      drupal_flush_all_caches();
       drupal_set_message($this->t('The configuration options have been saved.'));
     }
 
diff --git a/core/modules/system/src/Form/ModulesListForm.php b/core/modules/system/src/Form/ModulesListForm.php
index c1b2b73..23505fa 100644
--- a/core/modules/system/src/Form/ModulesListForm.php
+++ b/core/modules/system/src/Form/ModulesListForm.php
@@ -511,7 +511,6 @@ public function submitForm(array &$form, FormStateInterface $form_state) {
     // Gets module list after install process, flushes caches and displays a
     // message if there are changes.
     if ($before != $this->moduleHandler->getModuleList()) {
-      drupal_flush_all_caches();
       drupal_set_message(t('The configuration options have been saved.'));
     }
   }
diff --git a/core/modules/system/src/Tests/Routing/RouterTest.php b/core/modules/system/src/Tests/Routing/RouterTest.php
index 05f86f7..827471b 100644
--- a/core/modules/system/src/Tests/Routing/RouterTest.php
+++ b/core/modules/system/src/Tests/Routing/RouterTest.php
@@ -191,7 +191,7 @@ public function testControllerResolutionAjax() {
    */
   public function testRouterUninstall() {
     \Drupal::moduleHandler()->uninstall(array('router_test'));
-    $route_count = \Drupal::database()->query('SELECT COUNT(*) FROM {router} WHERE name = :route_name', array(':route_name' => 'router_test.1'))->fetchField();
-    $this->assertEqual(0, $route_count, 'All router_test routes have been removed on uninstall.');
+    $route = \Drupal::service('router.route_provider')->getRouteByName('router_test.1');
+    $this->assertNull($route, 'All router_test routes have been removed on uninstall.');
   }
 }
diff --git a/core/modules/system/src/Tests/System/ThemeTest.php b/core/modules/system/src/Tests/System/ThemeTest.php
index e1b091d..5078156 100644
--- a/core/modules/system/src/Tests/System/ThemeTest.php
+++ b/core/modules/system/src/Tests/System/ThemeTest.php
@@ -244,8 +244,6 @@ function testSwitchDefaultTheme() {
     $this->clickLink(t('Set as default'));
     $this->assertEqual(\Drupal::config('system.theme')->get('default'), 'bartik');
 
-    drupal_flush_all_caches();
-
     // Test the default theme on the secondary links (blocks admin page).
     $this->drupalGet('admin/structure/block');
     $this->assertText('Bartik(' . t('active tab') . ')', 'Default local task on blocks admin page is the default theme.');