After login pops up error stating that ./../VAADIN/vaadinBootstrap.js cannot be found. This can be only reproduced with Tomcat as it appends jsessionid to url which causes the problem.

From HipChat:
This is the root reason for jsession problem. Vaadin 7 bootstrap tries to find js file from relative URL. It fails because browser interprets last part of url containing ";" as a directory and relative referencing fails because it goes one level too high thus encountering 404
"admincentral;jsessionid=" = bad, "admincentral?jsessionid=" = good, "admincentral" = good