The usage /dashboard/index/<PROJECT_KEY> can be a problem when a project contains some slash (for branches for instance), as the project won't be displayed.
The URL should be replaced by /dashboard?id=<PROJECT_KEY>.
This problem can be solved on Apache by using the following configuration :
(See http://i-proving.com/2014/01/20/tomcat-apachehttpd-encoded-slashes-problem/ for more detail)
But it may be unsafe to use this option.