Upgrade an ASP.NET Web Application to ASP.NET 4.0
Upgrade an Application's Web.config File from the .NET Framework 3.5 to the .NET Framework 4 1. Make sure that the application currently targets ASP.NET 3.5.
2. Open the Web.config file in the application root.
3. In the configSections section, remove the sectionGroup element that is named "system.web.extensions".
4. In the system.web section, in the compilation collection, remove every add element that refers to an assembly of the .NET Framework.
Framework assemblies generally begin
