Session expired...


I deployed a Vaadin application on Glassfish 4. The sessiontimeout of the glassfish is set to 480 seconds via web.xml. “ProductionMode” is set to “false”, the HeartbeatInterval is set to 15 seconds and idle sessions should be closed:


However, sometimes it occures, that the session is expired after some seconds. With the network console, I can see, that the last heartbeatIntervall fails. I got the error attached in the screenshot.

I am using vaadin 7.1.11. If you need further information, please tell me what do you need.