jpackage on Windows seemed to have problems with the non-standard Graal JDK file name. This would result in an extra directory being inserted something like... runtime graalvm-ce-java11 bin conf ... instead of... runtime bin conf ... To workaround this I renamed the graal jvm to java-11. Despite the jdk-11 runtime being first in the PATH environment variable the jdk-16 one was default chosen to embed. So '--runtime-image /path/to/jdk-11' was required. The installation then ran without problems, no additional directory was inserted.