diff --git a/www/on/%platform/%user_name/failure.html.spt b/www/on/%platform/%user_name/failure.html.spt
index 2e9e61449d..15fde49b6c 100644
--- a/www/on/%platform/%user_name/failure.html.spt
+++ b/www/on/%platform/%user_name/failure.html.spt
@@ -9,6 +9,7 @@ if platform is None:
 user_name = path['user_name']
 if not user_name:
     raise Response(400, '%user_name is empty')
+platform.get_user_info(user_name) # raises 404 if user_name is unknown
 
 try:
     action = qs['action']