playframework ProtocolException invalid message

Question

I have a funny phenomenon:

If I start a blank index.html page with this controller:

public class Application extends Controller {
    public static void index() {
        render();
    }
}

I don't see the index page but get the offer to download a file with this content:

FHcodeProtocolExceptionmessageinvalid message tagZ

What is the magic here?

Answer 1

Try to change the HTTP port in your application.conf (default is set to 9000).