Ich habe mein WebApi OAuth 2.0 folgendermaßen konfiguriert:

    app.UseOAuthBearerAuthentication(new OAuthBearerAuthenticationOptions
    {
        Provider = new OAuthBearerAuthenticationProvider(),
    });

    app.UseOAuthBearerTokens(OAuthOptions);

Aber es gibt mir den folgenden Fehler bei jeder Anfrage:

Message : An error has occurred.
ExceptionMessage : Sequence contains more than one element
ExceptionType : System.InvalidOperationException
StackTrace :    at System.Linq.Enumerable.SingleOrDefault[TSource](IEnumerable`1 source)
   at Microsoft.Owin.Security.AuthenticationManager.d__8.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at System.Web.Http.HostAuthenticationFilter.d__0.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Web.Http.Controllers.AuthenticationFilterResult.d__0.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at System.Web.Http.Dispatcher.HttpControllerDispatcher.d__1.MoveNext()

MeineOAuthOptions ist:

    OAuthOptions = new OAuthAuthorizationServerOptions
    {
        TokenEndpointPath = new PathString("/Token"),
        Provider = new ApplicationOAuthProvider(PublicClientId, UserManagerFactory),
        AuthorizeEndpointPath = new PathString("/Account/ExternalLogin"),
        AccessTokenExpireTimeSpan = TimeSpan.FromDays(14),
        AllowInsecureHttp = true,
    };
}

Wenn ich kommentiereUseOAuthBearerAuthentication alles ist ok! Ich habe den OAuthBearerAuthenticationProvider noch nicht angepasst und verwende ihn direkt. Warum erhalte ich eine Fehlermeldung?