Issues packaging FXML application in How Do I? Posted October 16, 2018 · Report reply Actually, Excelsior JET Maven plugin invokes JetPackII itself (xpack actually -- batch mode packager). So you do not need to run it separately. In your case "javafx-swing" runtime component should be added via Excelsior JET Maven configuration as described here: https://github.com/excelsior-oss/excelsior-jet-maven-plugin/wiki/Excelsior-JET-Runtime-Configurations#optional-components To avoid such problems, it is highly recommended to perform Test Run before build to discover required JET Runtime components that are loaded by your application dynamically. Maven command for Test Run is "jet:testrun"