reverted:
--- b/core/modules/views/lib/Drupal/views/Tests/Plugin/ExposedFormTest.php
+++ a/core/modules/views/lib/Drupal/views/Tests/Plugin/ExposedFormTest.php
@@ -21,7 +21,7 @@
    *
    * @var array
    */
+  public static $testViews = array('test_exposed_form_buttons', 'test_exposed_block');
-  public static $testViews = array('test_exposed_form_buttons', 'test_exposed_block', 'test_exposed_form');
 
   /**
    * Modules to enable.
@@ -174,20 +174,4 @@
     return drupal_clean_css_identifier('views-exposed-form-' . $view->storage->id() . '-' . $view->current_display);
   }
 
-  /**
-   * Tests a view which is rendered after a form with a validation error.
-   */
-  public function testFormErrorWithExposedForm() {
-    $nodes = array();
-    $nodes[] = $this->drupalCreateNode();
-    $nodes[] = $this->drupalCreateNode();
-
-    $this->drupalGet('test-form');
-    $this->assertRaw(t('Apply'), 'Ensure the exposed form is rendered before submitting the normal form.');
-
-    $this->drupalPost(NULL, array(), t('Submit'));
-    $this->assertRaw(t('Apply'), 'Ensure the exposed form is rendered after submitting the normal form.');
-
-  }
-
 }
reverted:
--- b/core/modules/views/lib/Drupal/views/ViewExecutable.php
+++ a/core/modules/views/lib/Drupal/views/ViewExecutable.php
@@ -1076,16 +1076,8 @@
 
     if ($this->display_handler->usesExposed()) {
       $exposed_form = $this->display_handler->getPlugin('exposed_form');
-      // (1) Record the errors before rendering the exposed form widgets
-      $errors_before = \Drupal::formBuilder()->getAnyErrors();
       $this->exposed_widgets = $exposed_form->renderExposedForm();
+      if (\Drupal::formBuilder()->getAnyErrors() || !empty($this->build_info['abort'])) {
-      // (2) Record the errors after rendering the exposed form widgets.
-      $errors_after = \Drupal::formBuilder()->getAnyErrors();
-      // Find out if the validation of any of the elements in the exposed form
-      // has failed by comparing (1) and (2) above. Don't mess with the view
-      // otherwise.
-      $exposed_errors = count($errors_after) > count($errors_before);
-      if ($exposed_errors || !empty($this->build_info['abort'])) {
         $this->built = TRUE;
         // Don't execute the query, $form_state, but rendering will still be executed to display the empty text.
         $this->executed = TRUE;
only in patch2:
unchanged:
--- a/core/modules/views/src/Tests/Plugin/ExposedFormTest.php
+++ b/core/modules/views/src/Tests/Plugin/ExposedFormTest.php
@@ -21,7 +21,7 @@ class ExposedFormTest extends ViewTestBase {
    *
    * @var array
    */
-  public static $testViews = array('test_exposed_form_buttons', 'test_exposed_block');
+  public static $testViews = array('test_exposed_form_buttons', 'test_exposed_block', 'test_exposed_form');
 
   /**
    * Modules to enable.
@@ -198,4 +198,20 @@ protected function getExpectedExposedFormId(ViewExecutable $view) {
     return drupal_clean_css_identifier('views-exposed-form-' . $view->storage->id() . '-' . $view->current_display);
   }
 
+  /**
+   * Tests a view which is rendered after a form with a validation error.
+   */
+  public function testFormErrorWithExposedForm() {
+    $nodes = array();
+    $nodes[] = $this->drupalCreateNode();
+    $nodes[] = $this->drupalCreateNode();
+
+    $this->drupalGet('test-form');
+    $this->assertRaw(t('Apply'), 'Ensure the exposed form is rendered before submitting the normal form.');
+
+    $this->drupalPost(NULL, array(), t('Submit'));
+    $this->assertRaw(t('Apply'), 'Ensure the exposed form is rendered after submitting the normal form.');
+
+  }
+
 }
only in patch2:
unchanged:
--- a/core/modules/views/src/ViewExecutable.php
+++ b/core/modules/views/src/ViewExecutable.php
@@ -1076,8 +1076,16 @@ public function build($display_id = NULL) {
 
     if ($this->display_handler->usesExposed()) {
       $exposed_form = $this->display_handler->getPlugin('exposed_form');
+      // (1) Record the errors before rendering the exposed form widgets
+      $errors_before = \Drupal::formBuilder()->getAnyErrors();
       $this->exposed_widgets = $exposed_form->renderExposedForm();
-      if (\Drupal::formBuilder()->getAnyErrors() || !empty($this->build_info['abort'])) {
+      // (2) Record the errors after rendering the exposed form widgets.
+      $errors_after = \Drupal::formBuilder()->getAnyErrors();
+      // Find out if the validation of any of the elements in the exposed form
+      // has failed by comparing (1) and (2) above. Don't mess with the view
+      // otherwise.
+      $exposed_errors = count($errors_after) > count($errors_before);
+      if ($exposed_errors || !empty($this->build_info['abort'])) {
         $this->built = TRUE;
         // Don't execute the query, $form_state, but rendering will still be executed to display the empty text.
         $this->executed = TRUE;