WCF - Error 500.21 Handler "svc-Integrated" has a bad module "ManagedPipelineHandler" in its module list" If you see this error you havent installed the prerequistes for ASP.NET 4. Try this Open Visual Studio Command Prompt Type the following: aspnet_regiis.exe -i Run the command Try your service again... Happy Face - it should be working :-) This basically installs the necess..