Thanks to suggestions in https://issues.jboss.org/browse/JBIDE-11374, the default value of <local.site> will now point into the user's ~/.m2 cache, and when using -Plocal.site w/o a -Dlocal.site=file:/// override, you'll get notification from Tycho if that default folder doesn't exist (yet), ie., because you need to fetch a new target platform.