Hi,
I’m using vaadin 7.6.0.beta1 and since then, sometimes, I have this new NullPointerException :
at com.vaadin.ui.ConnectorTracker.removeUnregisteredConnectors(ConnectorTracker.java:342)
at com.vaadin.ui.ConnectorTracker.cleanConnectorMap(ConnectorTracker.java:286)
at com.vaadin.server.communication.UidlWriter.write(UidlWriter.java:333)
at com.vaadin.server.communication.UIInitHandler.[b]
getInitialUidl
/b
at com.vaadin.server.communication.UIInitHandler.synchronizedHandleRequest(UIInitHandler.java:80)
at com.vaadin.server.SynchronizedRequestHandler.handleRequest(SynchronizedRequestHandler.java:41)
at com.vaadin.server.VaadinService.handleRequest(VaadinService.java:1409)
at com.vaadin.server.VaadinServlet.service(VaadinServlet.java:351)
…
I can’t reproduce it. It seems to happen at the arrival of the user on the application.
Any idea would be appreciated 
Best regards