diff -u b/core/themes/seven/seven.theme b/core/themes/seven/seven.theme
--- b/core/themes/seven/seven.theme
+++ b/core/themes/seven/seven.theme
@@ -123,7 +123,7 @@
       $variables['types'][$type->type]['url'] = url('node/add/' . $type->type);
     }
   } else {
-    $variables['add_content_type_url'] = url('admin/structure/types/add');
+    $variables['add_content_type_url'] = \Drupal::url('node.type_add');
   }
 }
 
@@ -176,8 +176,8 @@
  * gray.
  */
 function seven_preprocess_tablesort_indicator(&$variables) {
-  $variables['arrow_asc'] = url(drupal_get_path('theme','seven') . '/images/arrow-asc.png');
-  $variables['arrow_desc'] = url(drupal_get_path('theme','seven') . '/images/arrow-desc.png');
+  $variables['arrow_asc'] = file_create_url('/images/arrow-asc.png');
+  $variables['arrow_desc'] = file_create_url('/images/arrow-desc.png');
 }
 
 /**