My webstart client does not start (with log)

Probably you see something like

An error occurred while launching/running the application. Title: eXist XML-DB client Vendor: exist-db.org Category: Security Error Unsigned application requesting unrestricted access to system Unsigned resource: http://localhost:8080/exist/webstart/stax-api-1.0.1.jar

while the exception reads like:

JNLPException[category: Security Error : Exception: null : LaunchDesc: <jnlp spec="1.0+" codebase="http://localhost:8080/exist/webstart/" href="http://localhost:8080/exist/webstart/exist.jnlp">

The solution is to re-sign the jar files:

build.sh -f build/scripts/jarsigner.xml jnlp-unsign-all jnlp-sign-all