Microsoft SharePoint is not supported with version 4.0.30319.239 of the Microsoft .Net Runtime

Whenever you face an error
"Microsoft SharePoint is not supported with version 4.0.30319.239 of the Microsoft .Net Runtime".
Refer the following items:

Cause Of Error:
All server-side customizations directly for SharePoint 2010 need to be either the .NET Framework 3.5 or the .NET Framework 3.5 SP1. SharePoint 2010 doesn't support access from .NET Framework 4 or being run in a .NET Framework 4 app domain. When you try to run any update made in .NET Framework 4.0 or higher, you will face this error.

Solution:
Microsoft recommends that you develop a web service that uses the .NET Framework 4 and then connect to it from SharePoint.

Reference Link:
http://blogs.msdn.com/b/sharepointdev/archive/2011/07/14/net-framework-support-in-sharepoint-2010.aspx // Alpesh Shah