Migrating a Website from Visual Studio 2005 to Visual Studio 2008

The first time you open a Visual Studio 2005 website, you’ll be asked if you want to adjust it to use ASP.NET 3.5



If you choose Yes, the web.config file will be modified to target .NET 3.5. If you choose No, your website will continue targeting ASP.NET 2.0, but you can modify this detail at any time by choosing Website's Start Options. Either way, you won’t be asked again, because your preference is recorded in the hidden solution file that’s stored in a user-specific Visual Studio directory.