在WebSphere Application Server 8.5.5.0上部署之后，将从自定义MDB Java应用程序抛出以下错误消息。有什么想法吗？
CNTR0020E: EJB threw an unexpected (non-declared) exception during invocation of method "onMessage" on bean "BeanId(SWPortalMDB#SWPortalMDB.jar#MDBPortalBean, null)". Exception data: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:60)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:37)
at java.lang.reflect.Method.invoke(Method.java:611)
at com.ibm.ejs.jms.listener.ServerSessionDispatcher.dispatch(ServerSessionDispatcher.java:47)
at com.ibm.ejs.container.MDBWrapper.onMessage(MDBWrapper.java:100)
at com.ibm.ejs.container.MDBWrapper.onMessage(MDBWrapper.java:132)
at com.ibm.ejs.jms.listener.ServerSession.run(ServerSession.java:581)
at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1862)
Caused by: java.lang.NullPointerException
at com.ftc.fbapps.mdb.MDBPortalBean.onMessage(Unknown Source)
at com.ibm.ejs.jms.listener.MDBWrapper$PriviledgedOnMessage.run(MDBWrapper.java:309)
at com.ibm.ws.security.util.AccessController.doPrivileged(AccessController.java:63)