diff --git a/core/includes/common.inc b/core/includes/common.inc
index c294d9a..33a3f8b 100644
--- a/core/includes/common.inc
+++ b/core/includes/common.inc
@@ -493,7 +493,7 @@ function drupal_js_defaults($data = NULL) {
  */
 function drupal_process_attached(array $elements) {
   $build['#attached'] = $elements['#attached'];
-  \Drupal::service('renderer')->renderRoot($build);
+  \Drupal::service('renderer')->render($build);
 }
 
 /**
diff --git a/core/modules/system/src/Tests/Render/HtmlResponseAttachmentsTest.php b/core/modules/system/src/Tests/Render/HtmlResponseAttachmentsTest.php
index abb8e23..36a6e90 100644
--- a/core/modules/system/src/Tests/Render/HtmlResponseAttachmentsTest.php
+++ b/core/modules/system/src/Tests/Render/HtmlResponseAttachmentsTest.php
@@ -61,7 +61,6 @@ public function testAttachments() {
     $this->assertHeader('X-Drupal-Cache', 'HIT');
 
     // Now repeat all of the preceeding using drupal_process_attached().
-    debug('Now using drupal_process_attached().');
     // Test ['#attached']['http_header] = ['Status', $code].
     $this->drupalGet('/render_attached_test/teapot_dpa');
     $this->assertResponse(418);
@@ -160,7 +159,7 @@ protected function assertFeed() {
    */
   protected function assertHead() {
     // Discover the DOM element for the meta link.
-    $test_meta = $this->xpath('//head/meta[@test-attribute="testy"]');
+    $test_meta = $this->xpath('//head/meta[@test-attribute="testvalue"]');
     $this->assertEqual(1, count($test_meta), 'There\'s only one test attribute.');
     // Grab the only DOM element.
     $test_meta = reset($test_meta);
@@ -169,7 +168,7 @@ protected function assertHead() {
     }
     else {
       $test_meta_attributes = $test_meta->attributes();
-      $this->assertEqual($test_meta_attributes['test-attribute'], 'testy');
+      $this->assertEqual($test_meta_attributes['test-attribute'], 'testvalue');
     }
   }
 
diff --git a/core/modules/system/tests/modules/render_attached_test/src/Controller/TestController.php b/core/modules/system/tests/modules/render_attached_test/src/Controller/TestController.php
index 3d158b3..8e71bf0 100644
--- a/core/modules/system/tests/modules/render_attached_test/src/Controller/TestController.php
+++ b/core/modules/system/tests/modules/render_attached_test/src/Controller/TestController.php
@@ -51,7 +51,7 @@ public function head() {
       [
         '#tag' => 'meta',
         '#attributes' => [
-          'test-attribute' => 'testy',
+          'test-attribute' => 'testvalue',
         ],
       ],
       'test_head_attribute',