Angular 2 Failed to execute open on XMLHttpRequest: Invalid URL

If it's a 192.168.. type of url you should add a http:// or https:// in front of it. And you may need to enable CORS options on server side.

Another context when this error might happen is when using interceptors to set a base path. Something like the following:

@Injectable()
export class WithCredentialsInterceptor implements HttpInterceptor {

  constructor(private logger: LoggingService) {
  }

  intercept(request: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {

    // one way is to except / include only some urls by checking request.url

    const clonedRequest = request.clone({
      withCredentials: true
    });

    // this.logger.logTrace("Sending with credentials request: ", request.urlWithParams);
    return next.handle(clonedRequest);
  }
}

If this interceptor fires when a request to a full http/https url is provided to the http client, it will construct an invalid URL.

if you use localhost then only use http:// before your localhost

In my case, I was able to solve it by fixing the url for my http request from the client side instead of the serverside as echonax mentioned from missing http:// from localhost.

My issue was, in my request this.http.get(this.domain + '/api/prod/' + id).map(res => res.json())

I was missing a / from the front side of api. It should be /api