diff -u b/core/modules/aggregator/templates/aggregator-item.html.twig b/core/modules/aggregator/templates/aggregator-item.html.twig
--- b/core/modules/aggregator/templates/aggregator-item.html.twig
+++ b/core/modules/aggregator/templates/aggregator-item.html.twig
@@ -18,13 +18,13 @@
  * @ingroup themeable
  */
 #}
-<article class="feed-item {{ attributes.class }}">
+<article{{ attributes.addClass('feed-item') }}">
   <h2{{ title_attributes }}>
     <a href="{{ feed_url }}" rel="bookmark">{{ feed_title }}</a>
   </h2>
   {{ content }}
   <footer>
-    <time datetime="{{ createdtime|date("Y-m-d H:i") }}">
+    <time datetime="{{ posted_time|date("Y-m-d H:i") }}">
       {{ source_date }}
     </time>