Web.conﬁg setup to target 4.5 for correct C# with Example
The web.conﬁg system.web.httpRuntime must target 4.5 to ensure the thread will renter the request context before
resuming your async method.
Async and await have undeﬁned behavior on ASP.NET prior to 4.5. Async / await will resume on an arbitrary thread
that may not have the request context. Applications under load will randomly fail with null reference exceptions
accessing the HttpContext after the await. Using HttpContext.Current in WebApi is dangerous because of async