diff --git a/aspnetcore/mvc/views/tag-helpers/built-in/script-tag-helper.md b/aspnetcore/mvc/views/tag-helpers/built-in/script-tag-helper.md
index 18f2bfa683..f67ac9ce5e 100644
--- a/aspnetcore/mvc/views/tag-helpers/built-in/script-tag-helper.md
+++ b/aspnetcore/mvc/views/tag-helpers/built-in/script-tag-helper.md
@@ -4,7 +4,7 @@ author: rick-anderson
 ms.author: riande
 description: Discover the ASP.NET Core Script Tag Helper attributes and the role each attribute plays in extending behavior of the HTML Script tag.
 ms.custom: mvc
-ms.date: 12/18/2018
+ms.date: 12/02/2019
 uid: mvc/views/tag-helpers/builtin-th/script-tag-helper
 ---
 # Script Tag Helper in ASP.NET Core
@@ -28,6 +28,8 @@ The following Razor markup shows a `script` element with a fallback:
 </script>
 ```
 
+Don't use the `<script>` element's [defer](https://developer.mozilla.org/docs/Web/HTML/Element/script) attribute to defer loading the CDN script. The Script Tag Helper renders JavaScript that immediately executes the [asp-fallback-test](#asp-fallback-test) expression. The expression fails if loading the CDN script is deferred.
+
 ## Commonly used Script Tag Helper attributes
 
 See [Script Tag Helper](xref:Microsoft.AspNetCore.Mvc.TagHelpers.ScriptTagHelper) for all the Script Tag Helper attributes, properties, and methods.