My solution has 4 projects; one of the projects is a class library (dll) called HelperClass. Within HelperClass, there's a class called Conversionswith static method public static System.IO.Stream ConvertToJson(DataTable)
Within this static method, I instantiate with JavaScriptSerializer javaScriptSerializer = new JavaScriptSerializer();. When I uncomment that line, all calls from all projects that reference the HelperClass library immediately break; the project is not recognized. I comment it back and everything returns to normal.
Even though it turns out that I didn't have to use JavaScriptSerializer, I would still like to know why this happens.
I've read to change the project target framework to .NET Framework 4 - Client Profile. With all the warnings I get, I ended up not doing it.
Thanks.
Make sure all your projects are set to the full .net profile not Client. Right click the projects and click properties it the dropdown on the first page.