diff --git a/core/modules/taxonomy/lib/Drupal/taxonomy/Controller/TermAutocompleteController.php b/core/modules/taxonomy/lib/Drupal/taxonomy/Controller/TermAutocompleteController.php
index f14ea0e..cdd2a08 100644
--- a/core/modules/taxonomy/lib/Drupal/taxonomy/Controller/TermAutocompleteController.php
+++ b/core/modules/taxonomy/lib/Drupal/taxonomy/Controller/TermAutocompleteController.php
@@ -13,6 +13,9 @@
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\Response;
 use Symfony\Component\HttpFoundation\JsonResponse;
+use Drupal\Component\Utility\Tags;
+use Drupal\Component\Utility\Unicode;
+use Drupal\Component\Utility\String;
 
 /**
  * Returns responses for Views UI routes.
@@ -84,13 +87,13 @@ public function autocomplete(Request $request, $field_name) {
     if (!($field = field_info_field($field_name)) || $field['type'] !== 'taxonomy_term_reference') {
       // Error string. The JavaScript handler will realize this is not JSON and
       // will display it as debugging information.
-      return new Response(t('Taxonomy field @field_name not found.', array('@field_name' => $field_name)));
+      return new Response(t('Taxonomy field @field_name not found.', array('@field_name' => $field_name)), 403);
     }
 
     // The user enters a comma-separated list of tags. We only autocomplete the
     // last tag.
-    $tags_typed = drupal_explode_tags($tags_typed);
-    $tag_last = drupal_strtolower(array_pop($tags_typed));
+    $tags_typed = Tags::explode($tags_typed);
+    $tag_last = Unicode::strtolower(array_pop($tags_typed));
 
     $matches = array();
     if ($tag_last != '') {
@@ -125,7 +128,7 @@ public function autocomplete(Request $request, $field_name) {
         if (strpos($name, ',') !== FALSE || strpos($name, '"') !== FALSE) {
           $n = '"' . str_replace('"', '""', $name) . '"';
         }
-        $matches[$prefix . $n] = check_plain($name);
+        $matches[$prefix . $n] = String::checkPlain($name);
       }
     }