Vaadin - url mapping and javascript files

If you are developing a Vaadin-based application and you are getting an error like this:

Failed to load the bootstrap javascript: ./VAADIN/vaadinBootstrap.js

you should have a look to your web.xml! Vaadin couldn't find the javascriptfile as expected.
Maybe you've defined some servlet-mapping that's not matching with the vaadin defaults. Just change your mapping to:

 
  simpleapp
  /*
 

and see if things are working correctly now. For more details see Vaadin ticket#10122