Glassfish can't run with Mustang beta due to collision of stax related classes as part of standalone stax distribution (sjsxp.jar) and stax classes as part of Mustang. Standalone stax distriubution (Sun Java Streaming XML Parser) has classes in different packgae than classes in JDK except classes under com.sun.xml.stream.** . Due to this when any app. places sjsxp.jar is placed in classpath running on Mustang, it causes problem because factory is loaded from sjsxp.jar but few classes are loaded from JVM.