Hello, I am now using JBoss 3.2.8 as server, which is hosting a 3rd party API called JBilling, which used EjB2.xand my client (EJB 3.0) is based on Jboss 4.0.5. When I try to connect to the server I get an exception, the stacktrace is given below. I checked the jars containing the class org.jboss.util.id.GUID on both JBoss's, the same version of the class is present on both servers. What could be the reason for getting this exception? Thanks 17:21:25,261 ERROR [STDERR] com.sapienter.jbilling.server.util.api.JbillingAPIException: java.lang.ClassCastException: org.jboss.util.id.GUID cannot be cas t to org.jboss.util.id.GUID 17:21:25,276 ERROR [STDERR] at com.sapienter.jbilling.server.util.api.EJBAPI.(EJBAPI.java:53) 17:21:25,276 ERROR [STDERR] at com.sapienter.jbilling.server.util.api.JbillingAPIFactory.getAPI(JbillingAPIFactory.java:56) 17:21:25,276 ERROR [STDERR] at com.stratoshear.webinterface.ui.SubscriberHandler.populateSubscriberDetails(Unknown Source) 17:21:25,292 ERROR [STDERR] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 17:21:25,292 ERROR [STDERR] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) 17:21:25,292 ERROR [STDERR] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) 17:21:25,308 ERROR [STDERR] at java.lang.reflect.Method.invoke(Method.java:597) 17:21:25,308 ERROR [STDERR] at com.sun.faces.el.MethodBindingImpl.invoke(MethodBindingImpl.java:126) 17:21:25,323 ERROR [STDERR] at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:72) 17:21:25,323 ERROR [STDERR] at javax.faces.component.UICommand.broadcast(UICommand.java:312) 17:21:25,323 ERROR [STDERR] at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:267) 17:21:25,339 ERROR [STDERR] at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:381) 17:21:25,339 ERROR [STDERR] at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:75) 17:21:25,355 ERROR [STDERR] at com.sun.faces.lifecycle.LifecycleImpl.phase(LifecycleImpl.java:200) 17:21:25,355 ERROR [STDERR] at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:90) 17:21:25,355 ERROR [STDERR] at javax.faces.webapp.FacesServlet.service(FacesServlet.java:197) 17:21:25,370 ERROR [STDERR] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252) 17:21:25,370 ERROR [STDERR] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173) 17:21:25,370 ERROR [STDERR] at org.apache.myfaces.component.html.util.ExtensionsFilter.doFilter(ExtensionsFilter.java:112) 17:21:25,386 ERROR [STDERR] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202) 17:21:25,386 ERROR [STDERR] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173) 17:21:25,401 ERROR [STDERR] at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96) 17:21:25,401 ERROR [STDERR] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202) 17:21:25,401 ERROR [STDERR] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173) 17:21:25,417 ERROR [STDERR] at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213) 17:21:25,417 ERROR [STDERR] at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178) 17:21:25,417 ERROR [STDERR] at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:175) 17:21:25,433 ERROR [STDERR] at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:74) 17:21:25,433 ERROR [STDERR] at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126) 17:21:25,448 ERROR [STDERR] at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105) 17:21:25,448 ERROR [STDERR] at org.jboss.web.tomcat.tc5.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:156) 17:21:25,448 ERROR [STDERR] at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107) 17:21:25,464 ERROR [STDERR] at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148) 17:21:25,464 ERROR [STDERR] at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:869) 17:21:25,464 ERROR [STDERR] at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:664) 17:21:25,480 ERROR [STDERR] at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527) 17:21:25,480 ERROR [STDERR] at org.apache.tomcat.util.net.MasterSlaveWorkerThread.run(MasterSlaveWorkerThread.java:112) 17:21:25,495 ERROR [STDERR] at java.lang.Thread.run(Thread.java:619) View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4083919#... 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