diff --git a/core/authorize.php b/core/authorize.php
index ba71c5d..611cca8 100644
--- a/core/authorize.php
+++ b/core/authorize.php
@@ -20,6 +20,7 @@
  * @link authorize Authorized operation helper functions @endlink
  */
 
+use Drupal\Core\Page\DefaultHtmlPageRenderer;
 use Symfony\Component\HttpFoundation\Request;
 
 // Change the directory to the Drupal root.
@@ -156,13 +157,7 @@ function authorize_access_allowed() {
 
 if (!empty($output)) {
   drupal_add_http_header('Content-Type', 'text/html; charset=utf-8');
-  $maintenance_page = array(
-    '#page' => array(
-      '#title' => $page_title,
-    ),
-    '#theme' => 'maintenance_page',
-    '#content' => $output,
+  print DefaultHtmlPageRenderer::renderPage($output, $page_title, 'maintenance', array(
     '#show_messages' => $show_messages,
-  );
-  print drupal_render($maintenance_page);
+  ));
 }
diff --git a/core/includes/batch.inc b/core/includes/batch.inc
index daa7b2f..153a7de 100644
--- a/core/includes/batch.inc
+++ b/core/includes/batch.inc
@@ -16,6 +16,7 @@
 
 use Drupal\Component\Utility\Timer;
 use Drupal\Core\Batch\Percentage;
+use Drupal\Core\Page\DefaultHtmlPageRenderer;
 use Symfony\Component\HttpFoundation\JsonResponse;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\RedirectResponse;
@@ -121,18 +122,14 @@ function _batch_progress_page() {
     // the error message.
     ob_start();
     $fallback = $current_set['error_message'] . '<br />' . $batch['error_message'];
-    $fallback = array(
-      '#theme' => 'maintenance_page',
-      '#title' => $current_set['title'],
-      '#content' => $fallback,
-      '#show_messages' => FALSE,
-    );
 
     // We strip the end of the page using a marker in the template, so any
     // additional HTML output by PHP shows up inside the page rather than below
     // it. While this causes invalid HTML, the same would be true if we didn't,
     // as content is not allowed to appear after </html> anyway.
-    $fallback = drupal_render($fallback);
+    $fallback = DefaultHtmlPageRenderer::renderPage($fallback, $current_set['title'], 'maintenance', array(
+      '#show_messages' => FALSE,
+    ));
     list($fallback) = explode('<!--partial-->', $fallback);
     print $fallback;
 
diff --git a/core/includes/errors.inc b/core/includes/errors.inc
index 56c276f..56cf71a 100644
--- a/core/includes/errors.inc
+++ b/core/includes/errors.inc
@@ -5,6 +5,7 @@
  * Functions for error handling.
  */
 
+use Drupal\Core\Page\DefaultHtmlPageRenderer;
 use Drupal\Core\Utility\Error;
 use Drupal\Component\Utility\String;
 use Symfony\Component\HttpFoundation\Response;
@@ -231,12 +232,7 @@ function _drupal_log_error($error, $fatal = FALSE) {
         install_display_output($output, $GLOBALS['install_state']);
       }
       else {
-        $output = array(
-          '#theme' => 'maintenance_page',
-          '#title' => 'Error',
-          '#content' => $message,
-        );
-        $output = drupal_render($output);
+        $output = DefaultHtmlPageRenderer::renderPage($message, 'Error');
       }
 
       $response = new Response($output, 500);
diff --git a/core/includes/install.core.inc b/core/includes/install.core.inc
index a97387c..e089929 100644
--- a/core/includes/install.core.inc
+++ b/core/includes/install.core.inc
@@ -14,7 +14,7 @@
 use Drupal\Core\Installer\Exception\NoProfilesException;
 use Drupal\Core\Language\Language;
 use Drupal\Core\Language\LanguageManager;
-use Drupal\Core\Page\HtmlPage;
+use Drupal\Core\Page\DefaultHtmlPageRenderer;
 use Drupal\Core\StringTranslation\Translator\FileTranslation;
 use Drupal\Core\Extension\ExtensionDiscovery;
 use Drupal\Core\DependencyInjection\ContainerBuilder;
@@ -901,18 +901,10 @@ function install_display_output($output, $install_state) {
   );
   drupal_add_html_head($noindex_meta_tag, 'install_meta_robots');
 
-  $install_page = array(
-    '#type' => 'page',
-    '#theme' => 'install_page',
-    '#title' => $output['#title'],
-    'content' => array(
-      'system_main' => $output,
-    ),
-  );
-
   // Only show the task list if there is an active task; otherwise, the page
   // request has ended before tasks have even been started, so there is nothing
   // meaningful to show.
+  $regions = array();
   if (isset($install_state['active_task'])) {
     // Let the theming function know when every step of the installation has
     // been completed.
@@ -923,20 +915,10 @@ function install_display_output($output, $install_state) {
       '#active' => $active_task,
       '#variant' => 'install',
     );
-    $install_page['sidebar_first'] = $task_list;
+    $regions['sidebar_first'] = $task_list;
   }
 
-  // @see \Drupal\Core\Page\DefaultHtmlFragmentRenderer::render()
-  // @see \Drupal\system\Controller\BatchController::render()
-  $page = new HtmlPage('', array(), $output['#title']);
-  $page_array = drupal_prepare_page($install_page);
-
-  $page = \Drupal::service('html_fragment_renderer')->preparePage($page, $page_array);
-  $page->setBodyTop(drupal_render($page_array['page_top']));
-  $page->setBodyBottom(drupal_render($page_array['page_bottom']));
-  $page->setContent(drupal_render($page_array));
-
-  print \Drupal::service('html_page_renderer')->render($page);
+  print DefaultHtmlPageRenderer::renderPage($output, $output['#title'], 'install_page', $regions);
   exit;
 }
 
diff --git a/core/includes/update.inc b/core/includes/update.inc
index 0bca244..58e47ba 100644
--- a/core/includes/update.inc
+++ b/core/includes/update.inc
@@ -14,6 +14,7 @@
 use Drupal\Core\Config\FileStorage;
 use Drupal\Core\Config\ConfigException;
 use Drupal\Core\DrupalKernel;
+use Drupal\Core\Page\DefaultHtmlPageRenderer;
 use Drupal\Core\Utility\Error;
 use Drupal\Component\Uuid\Uuid;
 use Drupal\Component\Utility\NestedArray;
@@ -151,15 +152,9 @@ function update_check_requirements($skip_warnings = FALSE) {
       '#theme' => 'status_report',
       '#requirements' => $requirements,
     );
-    $status_report = drupal_render($status);
-    $status_report .= 'Check the messages and <a href="' . check_url(drupal_requirements_url($severity)) . '">try again</a>.';
+    $status_report['#suffix'] = 'Check the messages and <a href="' . check_url(drupal_requirements_url($severity)) . '">try again</a>.';
     drupal_add_http_header('Content-Type', 'text/html; charset=utf-8');
-    $maintenance_page = array(
-      '#theme' => 'maintenance_page',
-      '#title' => 'Requirements problem',
-      '#content' => $status_report,
-    );
-    print drupal_render($maintenance_page);
+    print DefaultHtmlPageRenderer::renderPage($status_report, 'Requirements problem');
     exit();
   }
 }
diff --git a/core/lib/Drupal/Core/Controller/ExceptionController.php b/core/lib/Drupal/Core/Controller/ExceptionController.php
index d79567c..9302ab9 100644
--- a/core/lib/Drupal/Core/Controller/ExceptionController.php
+++ b/core/lib/Drupal/Core/Controller/ExceptionController.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\Core\Controller;
 
+use Drupal\Core\Page\DefaultHtmlPageRenderer;
 use Drupal\Core\Page\HtmlPageRendererInterface;
 use Drupal\Core\StringTranslation\TranslationInterface;
 use Symfony\Component\DependencyInjection\ContainerAwareInterface;
@@ -353,15 +354,8 @@ public function on500Html(FlattenException $exception, Request $request) {
       drupal_set_message($message, $class, TRUE);
     }
 
-    $page_content = array(
-      '#theme' => 'maintenance_page',
-      '#content' => t('The website has encountered an error. Please try again later.'),
-      '#page' => array(
-        '#title' => t('Error'),
-      ),
-    );
-
-    $output = drupal_render($page_content);
+    $content = t('The website has encountered an error. Please try again later.');
+    $output = DefaultHtmlPageRenderer::renderPage($content, t('Error'));
     $response = new Response($output);
     $response->setStatusCode(500, '500 Service unavailable (with message)');
 
diff --git a/core/lib/Drupal/Core/EventSubscriber/MaintenanceModeSubscriber.php b/core/lib/Drupal/Core/EventSubscriber/MaintenanceModeSubscriber.php
index 93bfb42..93501d0 100644
--- a/core/lib/Drupal/Core/EventSubscriber/MaintenanceModeSubscriber.php
+++ b/core/lib/Drupal/Core/EventSubscriber/MaintenanceModeSubscriber.php
@@ -7,6 +7,8 @@
 
 namespace Drupal\Core\EventSubscriber;
 
+use Drupal\Component\Utility\String;
+use Drupal\Core\Page\DefaultHtmlPageRenderer;
 use Symfony\Component\HttpFoundation\RedirectResponse;
 use Symfony\Component\HttpFoundation\Response;
 use Symfony\Component\HttpKernel\KernelEvents;
@@ -44,14 +46,10 @@ public function onKernelRequestMaintenance(GetResponseEvent $event) {
     if ($request->attributes->get('_maintenance') != MENU_SITE_ONLINE && !($response instanceof RedirectResponse)) {
       // Deliver the 503 page.
       drupal_maintenance_theme();
-      $maintenance_page = array(
-        '#theme' => 'maintenance_page',
-        '#title' => t('Site under maintenance'),
-        '#content' => filter_xss_admin(
-          t(\Drupal::config('system.maintenance')->get('message'), array('@site' => \Drupal::config('system.site')->get('name')))
-        ),
-      );
-      $content = drupal_render($maintenance_page);
+      $content = filter_xss_admin(String::format(\Drupal::config('system.maintenance')->get('message'), array(
+        '@site' => \Drupal::config('system.site')->get('name'),
+      )));
+      $content = DefaultHtmlPageRenderer::renderPage($content, t('Site under maintenance'));
       $response = new Response('Service unavailable', 503);
       $response->setContent($content);
       $event->setResponse($response);
diff --git a/core/lib/Drupal/Core/Page/DefaultHtmlPageRenderer.php b/core/lib/Drupal/Core/Page/DefaultHtmlPageRenderer.php
index 821d42d..4ce4ab2 100644
--- a/core/lib/Drupal/Core/Page/DefaultHtmlPageRenderer.php
+++ b/core/lib/Drupal/Core/Page/DefaultHtmlPageRenderer.php
@@ -23,4 +23,60 @@ public function render(HtmlPage $page) {
     return drupal_render($render);
   }
 
+  /**
+   * Renders a page using a custom page theme hook and optional region content.
+   *
+   * Temporary shim to facilitate modernization progress for special front
+   * contollers (install.php, update.php, authorize.php), maintenance mode, and
+   * the exception handler.
+   *
+   * Do NOT use this method in your code. This method will be removed as soon
+   * as architecturally possible.
+   *
+   * @param array|string $main
+   *   A render array or string containing the main page content.
+   * @param string $title
+   *   (optional) The page title.
+   * @param string $theme
+   *   (optional) The theme hook to use for rendering the page. The given value
+   *   is appended with '_page' at this point, since ultimately this parameter
+   *   will be converted into a theme template suggestion; i.e., #theme becomes
+   *   'page--$theme'. Defaults to 'maintenance'.
+   * @param array $regions
+   *   (optional) Additional region content to add to the page.
+   *
+   * @return string
+   *   The rendered HTML page.
+   *
+   * @internal
+   */
+  public static function renderPage($main, $title = '', $theme = 'maintenance', array $regions = array()) {
+    if (!is_array($main)) {
+      $main = array('#markup' => $main);
+    }
+    $page = new HtmlPage('', array(), $title);
+    $page_array = array(
+      '#type' => 'page',
+      // @todo Change this into "page__$theme" and rename templates into
+      //   page--maintenance and page--install.
+      '#theme' => $theme . '_page',
+      '#title' => $title,
+      'content' => array(
+        'system_main' => $main,
+      ),
+    );
+    $page_array += $regions;
+    $page_array += element_info('page');
+
+    // Allow modules and themes to alter the page render array.
+    \Drupal::moduleHandler()->alter('page', $page_array);
+
+    $page = \Drupal::service('html_fragment_renderer')->preparePage($page, $page_array);
+    $page->setBodyTop(drupal_render($page_array['page_top']));
+    $page->setBodyBottom(drupal_render($page_array['page_bottom']));
+    $page->setContent(drupal_render($page_array));
+
+    return \Drupal::service('html_page_renderer')->render($page);
+  }
+
 }
diff --git a/core/themes/bartik/bartik.theme b/core/themes/bartik/bartik.theme
index 642674c..176b798 100644
--- a/core/themes/bartik/bartik.theme
+++ b/core/themes/bartik/bartik.theme
@@ -94,7 +94,6 @@ function bartik_preprocess_maintenance_page(&$variables) {
   if (!$variables['db_is_active']) {
     $variables['site_name'] = '';
   }
-  $variables['styles'] = new RenderWrapper('drupal_get_css');
   // Normally we could attach libraries via hook_page_alter(), but when the
   // database is inactive it's not called so we add them here.
   $libraries = array(
@@ -104,6 +103,7 @@ function bartik_preprocess_maintenance_page(&$variables) {
       ),
     ),
   );
+  drupal_render($libraries);
 
   // Set the options that apply to both page and maintenance page.
   _bartik_process_page($variables);
diff --git a/core/themes/bartik/templates/maintenance-page.html.twig b/core/themes/bartik/templates/maintenance-page.html.twig
index c885257..604e176 100644
--- a/core/themes/bartik/templates/maintenance-page.html.twig
+++ b/core/themes/bartik/templates/maintenance-page.html.twig
@@ -35,7 +35,7 @@
       <main id="content" class="column" role="main"><section class="section">
         <a id="main-content"></a>
         {% if title %}<h1 class="title" id="page-title">{{ title }}</h1>{% endif %}
-        {{ content }}
+        {{ page.content }}
         {% if messages %}
           <div id="messages"><div class="section clearfix">
             {{ messages }}
diff --git a/core/update.php b/core/update.php
index c94b4c5..4e423b7 100644
--- a/core/update.php
+++ b/core/update.php
@@ -16,6 +16,7 @@
 
 use Drupal\Component\Utility\Settings;
 use Drupal\Core\DrupalKernel;
+use Drupal\Core\Page\DefaultHtmlPageRenderer;
 use Drupal\Core\Update\Form\UpdateScriptSelectionForm;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\Response;
@@ -458,18 +459,8 @@ function update_task_list($active = NULL) {
   }
   else {
     drupal_add_http_header('Content-Type', 'text/html; charset=utf-8');
-    $maintenance_page = array(
-      '#theme' => 'maintenance_page',
-      // $output has to be rendered here, because the maintenance page template
-      // is not wrapped into the html template, which means that any #attached
-      // libraries in $output will not be loaded, because the wrapping HTML has
-      // been printed already.
-      '#content' => drupal_render($output),
+    print DefaultHtmlPageRenderer::renderPage($output, $output['#title'], 'maintenance', array(
       '#show_messages' => !$progress_page,
-    );
-    if (isset($output['#title'])) {
-      $maintenance_page['#page']['#title'] = $output['#title'];
-    }
-    print drupal_render($maintenance_page);
+    ));
   }
 }