Converting to ASP.NET 4
The topics in this section describe how to migrate to ASP.NET version 4 from previous ASP.NET versions. The .NET Framework 4 provides a high degree of backward compatibility. Most applications created by using the .NET Framework 2.0, the .NET Framework 3.0, or the .NET Framework 3.5 will run on the .NET Framework 4 with minimal modifications.
For information about how to migrate from platforms other than ASP or ASP.NET, see Videos on Migrating to ASP.NET on the ASP.NET Web site.