diff --git a/user_guide_src/source/incoming/controllers.rst b/user_guide_src/source/incoming/controllers.rst
index 8bc9e90d581f..15b3f8821616 100644
--- a/user_guide_src/source/incoming/controllers.rst
+++ b/user_guide_src/source/incoming/controllers.rst
@@ -412,6 +412,8 @@ without route definitions. The auto-routing is disabled by default.
 
 .. important:: Auto Routing (Legacy) routes a HTTP request with **any** HTTP method to a controller method.
 
+.. important:: If Auto Routing (Legacy) doesn't find the controller, it will throw page not found exception before the filter executes.
+
 Consider this URI::
 
     example.com/index.php/helloworld/