diff --git a/user_guide_src/source/concepts/factories.rst b/user_guide_src/source/concepts/factories.rst
index 4520d3a8cb43..8c69d13d897f 100644
--- a/user_guide_src/source/concepts/factories.rst
+++ b/user_guide_src/source/concepts/factories.rst
@@ -274,7 +274,7 @@ Config Caching
 
 .. important:: Do not use this feature unless you have carefully read this section
     and understand how this feature works. Otherwise, your application will not
-    function properly.
+    function properly. Escpecially when you using function ``config()``, you must extends ``BaseConfig``.
 
 To improve performance, Config Caching has been implemented.