I updated .NET from 3.5 to 4.0 version, but after updating the assembly System.Web doesn't work any more. 
I'm getting the following error:
Warning 1 Could not resolve assembly "System.Web". The assembly is not in the currently targeted framework ".NETFramework,Version=v4.0,Profile=Client". Please remove references to assemblies not in the targeted framework or consider retargeting your project.
Using the 3.5 version it works fine. How can I fix this?
 
     
     
     
    
 
     
    