If you are getting the following error:
The value for the 'compilerVersion' attribute in the provider options must be 'v4.0' or later if you are compiling for version 4.0 or later of the .NET Framework. To compile this Web application for version 3.5 or earlier of the .NET Framework, remove the 'targetFramework' attribute from the <compilation> element of the Web.config file.
Please remove the following line in your web.config to fix it:
<compilation targetFramework="4.0" />