Did a fresh checkout and build of eXist this morning, after deleting my source tree, and it worked fine: the resulting web app was functional in every detail (so I saved it, just in case). Did another checkout at the end of the day, and the JNLP link on the eXist page didn't work -- but inserting the name of the web application's directory into it gives you a working link. It seems that a change to the source in the repository triggered this problem, and the suspect file is /exist_from_svn/eXist/webapp/WEB-INF/controller-config.xml, which had been changed during the day. So now we have a suspect. I've stashed a copy of it; if and when a checkout DOES work correctly, we can compare the two, and report the exact bug (if they're different in a way that suggests they are the cause).