User-166373564 posted
Hi,
If you use Visual Studio to open a Web project that was developed for the .NET Framework 2.0, the .NET Framework 3.0, or the .NET Framework 3.5, Visual Studio can automatically perform all the changes to Web.config files that are required to be able to run
using .NET Framework version 4.
Please follow the steps in the link below to upgrade an application by using Visual Studio,
Upgrade an ASP.NET Web Application to ASP.NET 4
hope it helps you,
Kind regards