I got this error while trying to host a WCF service in an empty ASP.NET application. The whole solution was using .NET 4.5 platform, on IIS 8.5 running on Windows 8.1. The gotcha was to
Open up "Turn Windows Features on or off"
Go to WCF section under ASP.NET 4.5 advanced services
Check HTTP Activation.
You'll be asked to restart the system.
This should Fix the HTTP 500.19!
EDIT 11-FEB-2016 Just got an issue on Windows 10 Pro, IIS 10, This time, it was an HTTP 404.0. The fix is still the same, turn on "HTTP Activation" under Windows Features -> .NET Framework 4.6 Advanced Services -> WCF Services -> HTTP Activation