no such connector could be found

Vaadin 6 / 7 / 8
1

Hi,

Working with Vaadin 7 on a simple login form, I suddenly came across the following issue:

When clicking on the login button, I only get the following warning, and the ClickListener is not invoked:

WARNING: RPC call to com.vaadin.shared.ui.button.ButtonServerRpc.click received for connector 6 but no such connector could be found

When I add ?debug to the URL and highlight the button (using H) to print the details on server side, I get the following exception:

java.lang.NullPointerException
	at com.vaadin.server.AbstractCommunicationManager.highlightConnector(AbstractCommunicationManager.java:649)
	at com.vaadin.server.AbstractCommunicationManager.handleUidlRequest(AbstractCommunicationManager.java:558)
	at com.vaadin.server.VaadinServlet.service(VaadinServlet.java:315)
	at com.vaadin.server.VaadinServlet.service(VaadinServlet.java:201)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)

The only other thing I see in the debug window is this warning:

10:00:19:016 Widget set is built on version: 7.0.0
Warning: widgetset version 7.0.0 does not seem to match theme version

I don’t know if that can be related. I tried recompiling the widgetset but that didn’t change this warning.

How can I figure out what’s wrong? I tried undoing my latest changes to the code, but that didn’t help either.

2

Solved my own problem: apparently this is what you get if you override attach() but forget to call super.attach().

Wouldn’t it be possible for Vaadin to log a clearer error message?