diff --cc core/modules/file/file.module
index 06e71ae,36904fa..0000000
--- a/core/modules/file/file.module
+++ b/core/modules/file/file.module
diff --cc core/modules/file/src/Plugin/Field/FieldWidget/FileWidget.php
index ab0c6a8,db111fe..0000000
--- a/core/modules/file/src/Plugin/Field/FieldWidget/FileWidget.php
+++ b/core/modules/file/src/Plugin/Field/FieldWidget/FileWidget.php
@@@ -14,7 -14,7 +14,8 @@@ use Drupal\Core\Field\FieldStorageDefin
  use Drupal\Core\Field\WidgetBase;
  use Drupal\Core\Form\FormStateInterface;
  use Drupal\Core\Render\Element;
 +use Drupal\file\Element\ManagedFile;
+ use Drupal\Core\Url;
  
  /**
   * Plugin implementation of the 'file_generic' widget.
diff --git a/core/lib/Drupal/Core/Render/Element/RenderElement.php b/core/lib/Drupal/Core/Render/Element/RenderElement.php
index ab97106..a621234 100644
--- a/core/lib/Drupal/Core/Render/Element/RenderElement.php
+++ b/core/lib/Drupal/Core/Render/Element/RenderElement.php
@@ -250,8 +250,8 @@ public static function preRenderAjaxForm($element) {
 
       // Change path to URL.
       $settings['url'] = NULL;
-      if (isset($settings['url']) && ($url = $settings['url']) && $url instanceof Url) {
-        $settings['url'] = $url->setOptions($settings['options'])->toString();
+      if (isset($settings['url']) && $settings['url'] instanceof Url) {
+        $settings['url'] = $settings['url']->setOptions($settings['options'])->toString();
       }
       unset($settings['options']);
 
diff --git a/core/lib/Drupal/Core/Routing/NullRouteMatch.php b/core/lib/Drupal/Core/Routing/NullRouteMatch.php
index 3cf8b12..d8a1f26 100644
--- a/core/lib/Drupal/Core/Routing/NullRouteMatch.php
+++ b/core/lib/Drupal/Core/Routing/NullRouteMatch.php
@@ -63,4 +63,5 @@ public function getRawParameters() {
   public function getUrl() {
     return Url::fromRoute($this->getRouteName(), $this->getRawParameters()->all());
   }
+
 }
diff --git a/core/modules/file/src/Element/ManagedFile.php b/core/modules/file/src/Element/ManagedFile.php
index 7a9e05f..75bd1a4 100644
--- a/core/modules/file/src/Element/ManagedFile.php
+++ b/core/modules/file/src/Element/ManagedFile.php
@@ -9,6 +9,7 @@
 
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Render\Element\FormElement;
+use Drupal\Core\Url;
 use Drupal\file\Entity\File;
 
 /**
@@ -219,7 +220,7 @@ public static function processManagedFile(&$element, FormStateInterface $form_st
       }
 
       // Add the upload progress callback.
-      $element['upload_button']['#ajax']['progress']['path'] = 'file/progress/' . $upload_progress_key;
+      $element['upload_button']['#ajax']['progress']['url'] = Url::fromRoute('file.ajax_progress');
     }
 
     // The file upload field itself.
diff --git a/core/modules/update/src/UpdateManager.php b/core/modules/update/src/UpdateManager.php
index 0ae3851..0652430 100644
--- a/core/modules/update/src/UpdateManager.php
+++ b/core/modules/update/src/UpdateManager.php
@@ -149,8 +149,7 @@ public function projectStorage($key) {
     // On certain paths, we should clear the data and recompute the projects for
     // update status of the site to avoid presenting stale information.
     $route_names = array(
-      // @todo find out the corresponding route for that.
-      // case 'admin/appearance/update':
+      'update.theme_update',
       'system.modules_list',
       'system.theme_install',
       'update.module_update',
diff --git a/core/modules/views/views.theme.inc b/core/modules/views/views.theme.inc
index 7ede047..73d9185 100644
--- a/core/modules/views/views.theme.inc
+++ b/core/modules/views/views.theme.inc
@@ -305,7 +305,7 @@ function template_preprocess_views_view_summary(&$variables) {
     \Drupal::routeMatch()->getUrl()->setOption('alias', TRUE)->toString(),
     // Could be an alias.
     \Drupal::url('<current>'),
-    // Count be an alias.
+    // Could be an alias.
     \Drupal::routeMatch()->getUrl()->toString(),
   );
   $active_urls = array_combine($active_urls, $active_urls);
diff --git a/core/modules/views_ui/admin.inc b/core/modules/views_ui/admin.inc
index 45183a9..9102f7d 100644
--- a/core/modules/views_ui/admin.inc
+++ b/core/modules/views_ui/admin.inc
@@ -325,7 +325,7 @@ function views_ui_standard_display_dropdown(&$form, FormStateInterface $form_sta
  * information about the form.
  *
  * @return \Drupal\Core\Url
- *   The URl object pointing to the form URL.
+ *   The URL object pointing to the form URL.
  */
 function views_ui_build_form_url(FormStateInterface $form_state) {
   $ajax = !$form_state->get('ajax') ? 'nojs' : 'ajax';
diff --git a/core/modules/views_ui/src/ViewUI.php b/core/modules/views_ui/src/ViewUI.php
index 69e15a8..7261446 100644
--- a/core/modules/views_ui/src/ViewUI.php
+++ b/core/modules/views_ui/src/ViewUI.php
@@ -757,6 +757,8 @@ public function renderPreview($display_id, $args = array()) {
       $output .= $preview . drupal_render($table);
     }
 
+    // Ensure that we just remove an additional request we pushed earlier.
+    // This could happen if $errors was not empty.
     if ($request_stack->getCurrentRequest() != $current_request) {
       $request_stack->pop();
     }
diff --git a/core/tests/Drupal/Tests/Core/Routing/RouteMatchTest.php b/core/tests/Drupal/Tests/Core/Routing/RouteMatchTest.php
index e1ff386..b6c2b10 100644
--- a/core/tests/Drupal/Tests/Core/Routing/RouteMatchTest.php
+++ b/core/tests/Drupal/Tests/Core/Routing/RouteMatchTest.php
@@ -55,7 +55,6 @@ public function testRouteMatchFromRequest() {
     $this->assertSame(array('foo' => '1'), $route_match->getParameters()->all());
     $this->assertSame(array(), $route_match->getRawParameters()->all());
 
-
     // A routed request with parameter upcasting.
     $foo = new \stdClass();
     $foo->value = 1;