Known issues for ASP.NET with .NET 3.5 SP1 Just wanted to give a heads up on two issues that we are aware of that were introduced with .NET 3.5 SP1. Issue: The HtmlForm action attribute is now honored when defined in declarative markup. Reason: 3.5 SP1 added a settable Action property to the HtmlForm type. This new feature makes it much easier for developers to explicitly set the form’s action attribute for scenarios where a developer wants to use a different Url than the normal postback-generated Url. However this change also means that if the action attribute has been set in an .aspx page’s declarative markup, ASP.NET will use the setting from the markup when rendering a <form /> element.