diff --git a/core/lib/Drupal/Core/Render/Element/RenderElement.php b/core/lib/Drupal/Core/Render/Element/RenderElement.php
index e27a073..c6e78ad 100644
--- a/core/lib/Drupal/Core/Render/Element/RenderElement.php
+++ b/core/lib/Drupal/Core/Render/Element/RenderElement.php
@@ -237,8 +237,13 @@ public static function preRenderAjaxForm($element) {
       // One such substantial difference is form elements that use
       // #ajax['callback'] for determining which part of the form needs
       // re-rendering. For that, we have a special 'system/ajax' route.
+      $url = NULL;
+      if (!isset($settings['url']) && isset($settings['callback'])) {
+        $url = Url::fromRouteMatch(\Drupal::routeMatch());
+        $settings['options']['query']['magic_string_to_be_renamed'] = 'drupal_ajax_post';
+      }
       $settings += array(
-        'url' => isset($settings['callback']) ? Url::fromRouteMatch(\Drupal::routeMatch()) : NULL,
+        'url' => $url,
         'options' => array(),
         'dialogType' => 'ajax',
       );
diff --git a/core/modules/search/search.module b/core/modules/search/search.module
index 62db411..4cafb3e 100644
--- a/core/modules/search/search.module
+++ b/core/modules/search/search.module
@@ -853,19 +853,3 @@ function _search_find_match_with_simplify($key, $text, $boundary, $langcode = NU
   // If we get here, we couldn't find a match.
   return NULL;
 }
-
-/**
- * Implements hook_form_FORM_ID_alter() for the search_block_form form.
- *
- * Since the exposed form is a GET form, we don't want it to send the form
- * tokens. However, you cannot make this happen in the form builder function
- * itself, because the tokens are added to the form after the builder function
- * is called. So, we have to do it in a form_alter.
- *
- * @see \Drupal\search\Form\SearchBlockForm
- */
-function search_form_search_block_form_alter(&$form, FormStateInterface $form_state) {
-  $form['form_build_id']['#access'] = FALSE;
-  $form['form_token']['#access'] = FALSE;
-  $form['form_id']['#access'] = FALSE;
-}
diff --git a/core/modules/search/src/Form/SearchBlockForm.php b/core/modules/search/src/Form/SearchBlockForm.php
index e154863..b07557e 100644
--- a/core/modules/search/src/Form/SearchBlockForm.php
+++ b/core/modules/search/src/Form/SearchBlockForm.php
@@ -64,6 +64,7 @@ public function buildForm(array $form, FormStateInterface $form_state) {
     }
 
     $route = 'search.view_' . $entity_id;
+    $form['#pre_render'][] = [get_class(), 'removeFormTokens'];
     $form['#action'] = $this->url($route);
     $form['#token'] = FALSE;
     $form['#method'] = 'get';
@@ -89,6 +90,22 @@ public function buildForm(array $form, FormStateInterface $form_state) {
   }
 
   /**
+   * Remove form tokens from the search form.
+   *
+   * Since the exposed form is a GET form, we don't want it to send the form
+   * tokens. However, you cannot make this happen in the form builder function
+   * itself, because the tokens are added to the form after the builder function
+   * is called. So, we have to do it in a #pre_render.
+   */
+  public static function removeFormTokens($element) {
+    $element['form_build_key']['#access'] = FALSE;
+    $element['form_build_id']['#access'] = FALSE;
+    $element['form_token']['#access'] = FALSE;
+    $element['form_id']['#access'] = FALSE;
+    return $element;
+  }
+
+  /**
    * {@inheritdoc}
    */
   public function submitForm(array &$form, FormStateInterface $form_state) {
diff --git a/core/modules/search/src/Tests/SearchBlockTest.php b/core/modules/search/src/Tests/SearchBlockTest.php
index bf18056..e2b7265 100644
--- a/core/modules/search/src/Tests/SearchBlockTest.php
+++ b/core/modules/search/src/Tests/SearchBlockTest.php
@@ -69,11 +69,7 @@ public function testSearchFormBlock() {
     /** @var $search_page_repository \Drupal\search\SearchPageRepositoryInterface */
     $search_page_repository = \Drupal::service('search.search_page_repository');
     $entity_id = $search_page_repository->getDefaultSearchPage();
-    $this->assertEqual(
-      $this->getUrl(),
-      \Drupal::url('search.view_' . $entity_id, array(), array('query' => array('keys' => $terms['keys']), 'absolute' => TRUE)),
-      'Submitted to correct url.'
-    );
+    $this->assertUrl(\Drupal::url('search.view_' . $entity_id, array(), array('query' => array('keys' => $terms['keys']), 'absolute' => TRUE)));
 
     // Test an empty search via the block form, from the front page.
     $terms = array('keys' => '');
@@ -83,11 +79,7 @@ public function testSearchFormBlock() {
 
     // Confirm that the user is redirected to the search page, when form is
     // submitted empty.
-    $this->assertEqual(
-      $this->getUrl(),
-      \Drupal::url('search.view_' . $entity_id, array(), array('query' => array('keys' => ''), 'absolute' => TRUE)),
-      'Redirected to correct url.'
-    );
+    $this->assertUrl(\Drupal::url('search.view_' . $entity_id, array(), array('query' => array('keys' => ''), 'absolute' => TRUE)));
 
     // Test that after entering a too-short keyword in the form, you can then
     // search again with a longer keyword. First test using the block form.
diff --git a/core/modules/search/src/Tests/SearchConfigSettingsFormTest.php b/core/modules/search/src/Tests/SearchConfigSettingsFormTest.php
index a99ea45..6466014 100644
--- a/core/modules/search/src/Tests/SearchConfigSettingsFormTest.php
+++ b/core/modules/search/src/Tests/SearchConfigSettingsFormTest.php
@@ -178,9 +178,7 @@ function testSearchModuleDisabling() {
       // to this plugin's search results page.
       $terms = array('keys' => $info['keys']);
       $this->submitGetForm('node', $terms, t('Search'));
-      $current = $this->getURL();
-      $expected = \Drupal::url('search.view_' . $entity->id(), array(), array('query' => array('keys' => $info['keys']), 'absolute' => TRUE));
-      $this->assertEqual( $current, $expected, 'Block redirected to right search page');
+      $this->assertUrl(\Drupal::url('search.view_' . $entity->id(), array(), array('query' => array('keys' => $info['keys']), 'absolute' => TRUE)));
 
       // Try an invalid search path, which should 404.
       $this->drupalGet('search/not_a_plugin_path');
diff --git a/core/modules/system/src/Tests/Entity/Element/EntityAutocompleteElementFormTest.php b/core/modules/system/src/Tests/Entity/Element/EntityAutocompleteElementFormTest.php
index 0fdd9af..e561fe6 100644
--- a/core/modules/system/src/Tests/Entity/Element/EntityAutocompleteElementFormTest.php
+++ b/core/modules/system/src/Tests/Entity/Element/EntityAutocompleteElementFormTest.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\system\Tests\Entity\Element;
 
+use Drupal\Core\DependencyInjection\DependencySerializationTrait;
 use Drupal\Core\Entity\Element\EntityAutocomplete;
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Form\FormInterface;
@@ -23,6 +24,8 @@
  */
 class EntityAutocompleteElementFormTest extends EntityUnitTestBase implements FormInterface {
 
+  use DependencySerializationTrait;
+
   /**
    * User for testing.
    *
diff --git a/core/modules/views/src/Form/ViewsExposedForm.php b/core/modules/views/src/Form/ViewsExposedForm.php
index 29300af..358ac02 100644
--- a/core/modules/views/src/Form/ViewsExposedForm.php
+++ b/core/modules/views/src/Form/ViewsExposedForm.php
@@ -164,7 +164,7 @@ public function submitForm(array &$form, FormStateInterface $form_state) {
     $view->exposed_data = $form_state->getValues();
     $view->exposed_raw_input = [];
 
-    $exclude = array('submit', 'form_build_id', 'form_id', 'form_token', 'exposed_form_plugin', 'reset');
+    $exclude = array('submit', 'form_build_id', 'form_build_key', 'form_id', 'form_token', 'exposed_form_plugin', 'reset');
     /** @var \Drupal\views\Plugin\views\exposed_form\ExposedFormPluginBase $exposed_form_plugin */
     $exposed_form_plugin = $view->display_handler->getPlugin('exposed_form');
     $exposed_form_plugin->exposedFormSubmit($form, $form_state, $exclude);