Issue #2830326 by dww, mpdonadio, cebasqueira, Wim Leers, amateescu, …

…jungle, xjm, daffie, Pasqualle: Broken link to 'Put your site into maintenance mode' on update.php results in WSOD

(cherry picked from commit 240e303d6afea84fc713b8131fdf5ee98443e22e)

modules/system/src/Controller/DbUpdateController.php

@@ -216,8 +216,10 @@ protected function info(Request $request) {
     ];
 
     $info[] = $this->t("<strong>Back up your code</strong>. Hint: when backing up module code, do not leave that backup in the 'modules' or 'sites/*/modules' directories as this may confuse Drupal's auto-discovery mechanism.");
+    // @todo Simplify with https://www.drupal.org/node/2548095
+    $base_url = str_replace('/update.php', '', $request->getBaseUrl());
     $info[] = $this->t('Put your site into <a href=":url">maintenance mode</a>.', [
-      ':url' => Url::fromRoute('system.site_maintenance_mode')->toString(TRUE)->getGeneratedUrl(),
+      ':url' => Url::fromRoute('system.site_maintenance_mode')->setOption('base_url', $base_url)->toString(TRUE)->getGeneratedUrl(),
     ]);
     $info[] = $this->t('<strong>Back up your database</strong>. This process will change your database values and in case of emergency you may need to revert to a backup.');
     $info[] = $this->t('Install your new files in the appropriate location, as described in the handbook.');

modules/system/tests/src/Functional/UpdateSystem/UpdateScriptTest.php

@@ -641,6 +641,23 @@ public function testSuccessfulMultilingualUpdateFunctionality() {
     $this->assertResponse(200);
   }
 
+  /**
+   * Tests maintenance mode link on update.php.
+   */
+  public function testMaintenanceModeLink() {
+    $admin_user = $this->drupalCreateUser([
+      'administer software updates',
+      'access administration pages',
+      'administer site configuration',
+    ]);
+    $this->drupalLogin($admin_user);
+    $this->drupalGet($this->updateUrl, ['external' => TRUE]);
+    $this->assertResponse(200);
+    $this->clickLink('maintenance mode');
+    $this->assertResponse(200);
+    $this->assertEquals('Maintenance mode', $this->cssSelect('main h1')[0]->getText());
+  }
+
   /**
    * Helper function to run updates via the browser.
    */