Session expired directly after starting application

I have a Vaadin application which uses Server Push. I use Jetty Runner to start the application from a batch file. When I debug in Eclipse using Jetty Maven Plugin everything runs fine. But when I start the built application with Jetty Runner there is immediately an error message that the session expired.
If found this thread: []
( which looks like my problem but it seems to be not solved for me. I tried to use the suggested websocket dependencies but then another error message is appearing, saying
javax.servlet.ServletException: Not running on Jetty, JSR-356 support unavailable at org.eclipse.jetty.websocket.jsr356.server.deploy.WebSocketServerContainerInitializer.onStartup(
Is Vaadin working with Jetty Runner at all? Or is there a trick to avoid the second problem?

I think it is the same problem as in the link above but not yet solved for Jetty Runner. When I downgrade to Jetty Runner 9.3 it is working.