Vaadin requires cookies to work and does not expect JSESSIONID to be present in the URI. When it is things break.

We used to have a problem where logging in would result in a 404, this was fixed in MAGNOLIA-5382 and the request is now correctly routed to the servlet.

This exposes another problem, a problem this ticket fixes.

Vaadin fails to start showing an alert about it being unable to load vaadinBootstrap.js. This error message is used irregardless of which resource it fails to load. In our case its actually resources set using @JavaScript and @StyleSheet. The reason is that the client appends the resource name to location.href. Location.href contains the JSESSIONID so the URI ends up being /.magnolia/admincentral;JSESSIONID=123/APP/PUBLISHED/...

The client will only use location.href if a 'serviceUrl' has not been sent from the server. It is normally not sent. By modifying AdmincentralVaadinServlet to include a serviceUrl this problem goes away.