Render message in 404 page

aleksis/core/templates/404.html

@@ -7,8 +7,7 @@
     <div class="card red">
       <div class="card-content white-text">
         <i class="material-icons small left">error_outline</i>
-        <span class="card-title">{% trans "Error" %} (404): {% blocktrans %}The requested page or object was not
-          found.{% endblocktrans %}</span>
+        <span class="card-title">{{ exception }}</span>
         <p>
           {% blocktrans %}
             If you were redirected by a link on an external page,