How to Check Which Version of Microsoft .NET Framework is Installed in Windows? HTTP Error 401.1 - Unauthorized .Net web.config configuration Error message when you try to visit a Web page that is hosted on IIS 7.0: "HTTP Error 401.2 - Unauthorized" Windows Authentication not working on local IIS 7.5. Error 401.1 Get the username of the user accessing ASP.NET intranet page within local network Disable the ASP.NET v4.0 Extensionless URL feature on IIS 6.0