Swing(jFrame) can not initialize

For ./gradlew run …there should be some options in the build.gradle file that configure what is sent to Java when it is run. I don’t use the SDK myself nor any of the JME generated build.gradle files so I cannot check myself. But my guess is that it is sending parameter to Java execution that is causing things to fail for you… like whatever the start on main thread parameter is… or maybe that’s what it’s missing. Macs are sometimes kind of hostile to Java development, especially OpenGL development.