F# Web API - Exception has been thrown by the target of an invocation - web-services

Question

I am trying to create an F# web service using OWIN, I have found 2 tutorials online and both are give me the same error of "Exception has been thrown by the target of an invocation" on the same line of code but I can not figure out why this is happening
use server = WebApp.Start<Startup>(baseAddress)
Below is a a short piece of code I am using the second and more complex example can be found here on the forfunandprofit website example number 3
namespace FSharpWebAPIOwin
open Owin
open System.Web.Http
open System.Collections.Generic
open Microsoft.Owin.Hosting
open System
module main =
type Startup() =
member this.Configuration(app : IAppBuilder) =
let config = new HttpConfiguration()
let route = config.Routes.MapHttpRoute(
"Default",
"api/{controller}/{id}" )
route.Defaults.Add("id", RouteParameter.Optional )
app.UseWebApi(config) |> ignore
type HelloController() =
inherit ApiController()
member this.Get() =
"hello"
[<EntryPoint>]
let main argv =
let baseAddress = "http://localhost:8000"
use server = WebApp.Start<Startup>(baseAddress)
Console.WriteLine("Press enter to exit ... ")
Console.ReadLine() |> ignore
0
Exception Details
System.Reflection.TargetInvocationException was unhandled
HResult=-2146232828
Message=Exception has been thrown by the target of an invocation.
Source=mscorlib
StackTrace:
at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor)
at System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object[] parameters, Object[] arguments)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at System.Reflection.MethodBase.Invoke(Object obj, Object[] parameters)
at Owin.Loader.DefaultLoader.<>c__DisplayClass12.<MakeDelegate>b__b(IAppBuilder builder)
at Owin.Loader.DefaultLoader.<>c__DisplayClass1.<LoadImplementation>b__0(IAppBuilder builder)
at Microsoft.Owin.Hosting.Engine.HostingEngine.ResolveApp(StartContext context)
at Microsoft.Owin.Hosting.Engine.HostingEngine.Start(StartContext context)
at Microsoft.Owin.Hosting.Starter.DirectHostingStarter.Start(StartOptions options)
at Microsoft.Owin.Hosting.Starter.HostingStarter.Start(StartOptions options)
at Microsoft.Owin.Hosting.WebApp.StartImplementation(IServiceProvider services, StartOptions options)
at Microsoft.Owin.Hosting.WebApp.Start(StartOptions options)
at Microsoft.Owin.Hosting.WebApp.Start[TStartup](StartOptions options)
at Microsoft.Owin.Hosting.WebApp.Start[TStartup](String url)
at FSharpWebAPIOwin.main.main(String[] argv) in C:\Users\amulligan\Desktop\Api\ConsoleApplication2\ConsoleApplication2\Program.fs:line 30
InnerException: System.IO.FileLoadException
HResult=-2146234304
Message=Could not load file or assembly 'System.Web.Http, Version=5.2.3.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)
Source=ConsoleApplication2
FileName=System.Web.Http, Version=5.2.3.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35
FusionLog==== Pre-bind state information ===
LOG: User = CCS\amulligan
LOG: DisplayName = System.Web.Http, Version=5.2.3.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35
(Fully-specified)
LOG: Appbase = file:///C:/Users/amulligan/Desktop/Api/ConsoleApplication2/ConsoleApplication2/bin/Debug/
LOG: Initial PrivatePath = NULL
Calling assembly : ConsoleApplication2, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null.
LOG: This bind starts in default load context.
LOG: Using application configuration file: C:\Users\amulligan\Desktop\Api\ConsoleApplication2\ConsoleApplication2\bin\Debug\ConsoleApplication2.exe.config
LOG: Using host configuration file:
LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework\v4.0.30319\config\machine.config.
LOG: Post-policy reference: System.Web.Http, Version=5.2.3.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35
LOG: Attempting download of new URL file:///C:/Users/amulligan/Desktop/Api/ConsoleApplication2/ConsoleApplication2/bin/Debug/System.Web.Http.DLL.
WRN: Comparing the assembly name resulted in the mismatch: Major Version
ERR: Failed to complete setup of assembly (hr = 0x80131040). Probing terminated.
StackTrace:
at FSharpWebAPIOwin.main.Startup.Configuration(IAppBuilder app)
InnerException: