Widgetset does not contain implementation for null

Hi all,

I’ve encountered the following problem,

I’ve searched the forum, some related questions are posted but, in my case the widgetset is null. Actually i don’t use any add-on and extra widgetset. More interesting point is, the code works well in my local tomcat but when i deploy it to server, this error occurs.

Is there anyone has an idea about this issue?

I suspect your deployment server is serving /VAADIN statically and not from the Vaadin JAR, and has a version of the widgetset that does not match the Vaadin version you are using. Locally, the servlet fetches the widgetset and themes directly from the JAR as long as you are not serving them explicitly from elsewhere.

Try adding “?debug” after the application URL and see if it reports a version conflict.