diff --git a/core/includes/form.inc b/core/includes/form.inc
index d2cfd47..6fb0a94 100644
--- a/core/includes/form.inc
+++ b/core/includes/form.inc
@@ -378,7 +378,7 @@ function template_preprocess_form(&$variables) {
         // The style guide requires a serial comma.
         $starting_error_links .= ',';
       }
-      $message =  \Drupal::translation()->formatPlural($error_count,
+      $message = \Drupal::translation()->formatPlural($error_count,
         '1 error has been found: !last_error_link.',
         '@count errors have been found: !starting_error_links and !last_error_link.',
         [
diff --git a/core/modules/system/src/Tests/Form/ValidationTest.php b/core/modules/system/src/Tests/Form/ValidationTest.php
index fb0ac7e..2ad92eb 100644
--- a/core/modules/system/src/Tests/Form/ValidationTest.php
+++ b/core/modules/system/src/Tests/Form/ValidationTest.php
@@ -292,7 +292,21 @@ protected function assertErrorMessages($messages) {
       // Gather the element for checking the jump link section.
       $error_links[] = \Drupal::l($message['title'], Url::fromRoute('<none>', [], ['fragment' => 'edit-' . str_replace('_', '-', $message['key']), 'external' => TRUE]));
     }
-    $top_message = \Drupal::translation()->formatPlural(count($error_links), '1 error has been found', '@count errors have been found') . ': ' . implode(', ', $error_links);
+    $error_count = count($error_links);
+    $last_error_link = array_pop($error_links);
+    $starting_error_links = implode(', ', $error_links);
+    if ($error_count > 2) {
+      // The style guide requires a serial comma.
+      $starting_error_links .= ',';
+    }
+    $top_message = \Drupal::translation()->formatPlural($error_count,
+      '1 error has been found: !last_error_link.',
+      '@count errors have been found: !starting_error_links and !last_error_link.',
+      [
+        '!starting_error_links' => $starting_error_links,
+        '!last_error_link' => $last_error_link,
+      ]
+    );
     $this->assertRaw($top_message);
     $this->assertNoText(t('An illegal choice has been detected. Please contact the site administrator.'));
   }