Angular 2 http get not working, never reaches the server

I am using a working project of Angular 2 from a Pluralsight course as a reference to make my first app.

This exisiting app fetchs the data from a Json file.

private _productUrl = 'api/products/products.json';

constructor(private _http: Http) { }

getProducts(): Observable<IProduct[]> {
    return this._http.get(this._productUrl)
        .map((response: Response) => <IProduct[]> response.json())
        .do(data => console.log('All: ' +  JSON.stringify(data)))
        .catch(this.handleError);
}

If I modify the url to my own web service that runs locally "http://localhost:53785/api/Session" and run the angular 2 app, It never reaches the breakpoint that I set in my web service and I get "SyntaxError: Unexpected end of JSON input" error.

In the console I get:

"Failed to load resource: the server responded with a status of 500 (Internal Server Error)" Response _body : "" headers : Headers ok : false status : 500 statusText : "Internal Server Error" type : 2 url : "http://localhost:53785/api/Session" proto : Body

Does anyone know why cant I reach my web service?

Thanks