Hi, I got the SerializationException problem when JBoss 4.0.4 tries to activate a stateful session bean that was passivated (and hence serialized to a file unser [JBOSS-DIR]/server/all/tmp/sessions directory). I am not using enum. The error is as follows: Exception in thread "AWT-EventQueue-0" java.lang.RuntimeException: org.jboss.serial.exception.SerializationException: Could not create instance of org.hibernate.ejb.QueryImpl - org.hibernate.ejb.QueryImpl at org.jboss.ejb3.stateful.StatefulBeanContext.extractBeanAndInterceptors(StatefulBeanContext.java:365) at org.jboss.ejb3.stateful.StatefulBeanContext.getInstance(StatefulBeanContext.java:309) at org.jboss.ejb3.stateful.StatefulInstanceInterceptor.invoke(StatefulInstanceInterceptor.java:75) at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101) at org.jboss.aspects.security.AuthenticationInterceptor.invoke(AuthenticationInterceptor.java:78) at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101) at org.jboss.ejb3.ENCPropagationInterceptor.invoke(ENCPropagationInterceptor.java:47) at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101) at org.jboss.ejb3.asynchronous.AsynchronousInterceptor.invoke(AsynchronousInterceptor.java:106) at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101) at org.jboss.ejb3.stateful.StatefulContainer.dynamicInvoke(StatefulContainer.java:308) at org.jboss.aop.Dispatcher.invoke(Dispatcher.java:106) at org.jboss.aspects.remoting.AOPRemotingInvocationHandler.invoke(AOPRemotingInvocationHandler.java:82) at org.jboss.remoting.ServerInvoker.invoke(ServerInvoker.java:828) at org.jboss.remoting.ServerInvoker.invoke(ServerInvoker.java:681) at org.jboss.remoting.transport.socket.ServerThread.processInvocation(ServerThread.java:358) at org.jboss.remoting.transport.socket.ServerThread.dorun(ServerThread.java:412) at org.jboss.remoting.transport.socket.ServerThread.run(ServerThread.java:239) at org.jboss.remoting.RemoteClientInvoker.invoke(RemoteClientInvoker.java:190) at org.jboss.remoting.Client.invoke(Client.java:525) at org.jboss.remoting.Client.invoke(Client.java:488) at org.jboss.aspects.remoting.InvokeRemoteInterceptor.invoke(InvokeRemoteInterceptor.java:55) at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101) at org.jboss.aspects.tx.ClientTxPropagationInterceptor.invoke(ClientTxPropagationInterceptor.java:61) at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101) at org.jboss.aspects.security.SecurityClientInterceptor.invoke(SecurityClientInterceptor.java:55) at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101) at org.jboss.ejb3.remoting.IsLocalInterceptor.invoke(IsLocalInterceptor.java:65) at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101) at org.jboss.ejb3.stateful.StatefulRemoteProxy.invoke(StatefulRemoteProxy.java:133) at $Proxy4.report(Unknown Source) at uk.co.MyCompany.a.b.MyStatefulBean.report(MyStatefulBean.java:49) Somehow the deserialization in JBoss is not working during activation?? btw my server.log looks like this: 2006-11-24 13:41:59,486 DEBUG [org.jboss.remoting.transport.socket.ServerThread] WAKEUP in SERVER THREAD 2006-11-24 13:41:59,486 DEBUG [org.jboss.remoting.transport.socket.ServerThread] beginning dorun 2006-11-24 13:41:59,501 DEBUG [org.jboss.ejb3.cache.simple.StatefulSessionFilePersistenceManager] Attempting to activate; id=4sv39f-d5cdqc-euwcjwy9-1-euwleaex-e 2006-11-24 13:41:59,501 DEBUG [org.jboss.ejb3.cache.simple.StatefulSessionFilePersistenceManager] Reading session state from: C:\java\jboss-4.0.4.GA\server\all\tmp\sessions\MyStatefulBean-euwlcs60-c\4sv39f-d5cdqc-euwcjwy9-1-euwleaex-e.ser 2006-11-24 13:41:59,533 DEBUG [org.jboss.ejb3.cache.simple.StatefulSessionFilePersistenceManager] Removing passivated state file: C:\java\jboss-4.0.4.GA\server\all\tmp\sessions\MyStatefulBean-euwlcs60-c\4sv39f-d5cdqc-euwcjwy9-1-euwleaex-e.ser -------------------------------------------------------------------------------- ** SO: Any help greatly appreciated. redyz View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3988420#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...