SerialVersionUID's not matching

Question

Hi, here's my exception:
java.rmi.ServerException: RemoteException occurred in server thread; nested exception is:
java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is:
java.io.InvalidClassException: com.tsc.model.courts.County; local class incompatible: stream classdesc serialVersionUID = -2433655832140195139, local class serialVersionUID = -5449895978211640294
at sun.rmi.server.UnicastServerRef.dispatch(Unknown Source)
at sun.rmi.transport.Transport$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.Transport.serviceCall(Unknown Source)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(Unknown Source)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
at sun.rmi.transport.StreamRemoteCall.exceptionReceivedFromServer(StreamRemoteCall.java:247)
at sun.rmi.transport.StreamRemoteCall.executeCall(StreamRemoteCall.java:223)
at sun.rmi.server.UnicastRef.invoke(UnicastRef.java:126)
at com.inteflux.Session.SessionManager_Stub.putObject(Unknown Source)
at com.inteflux.Session.SessionControlBean.putValue(SessionControlBean.java:116)
at com.tsc.action.AbstractUserAction.putSessionValue(AbstractUserAction.java:69)
at com.tsc.action.agent.TimedBookOrderAction.payment(TimedBookOrderAction.java:172)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at com.opensymphony.xwork.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:353)
at com.opensymphony.xwork.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:208)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:182)
at com.tsc.interceptor.webwork.HibernateInterceptor.intercept(HibernateInterceptor.java:35)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:180)
at com.opensymphony.xwork.interceptor.DefaultWorkflowInterceptor.intercept(DefaultWorkflowInterceptor.java:117)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:180)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:32)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:180)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:32)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:180)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:32)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:180)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:32)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:180)
at com.opensymphony.webwork.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:171)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:180)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:32)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:180)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:32)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:180)
at com.opensymphony.xwork.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:146)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:180)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:32)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:180)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:32)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:180)
at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:32)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:180)
at com.opensymphony.xwork.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:94)
at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:180)
at com.opensymphony.xwork.DefaultActionProxy.execute(DefaultActionProxy.java:119)
at com.opensymphony.webwork.dispatcher.DispatcherUtils.serviceAction(DispatcherUtils.java:233)
at com.opensymphony.webwork.dispatcher.FilterDispatcher.doFilter(FilterDispatcher.java:198)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:362)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:856)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:744)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:80)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:684)
at java.lang.Thread.run(Thread.java:595)
Caused by: java.rmi.UnmarshalException: error unmarshalling arguments; nested exception is:
java.io.InvalidClassException: com.tsc.model.courts.County; local class incompatible: stream classdesc serialVersionUID = -2433655832140195139, local class serialVersionUID = -5449895978211640294
at sun.rmi.server.UnicastServerRef.dispatch(Unknown Source)
at sun.rmi.transport.Transport$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.Transport.serviceCall(Unknown Source)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(Unknown Source)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.io.InvalidClassException: com.tsc.model.courts.County; local class incompatible: stream classdesc serialVersionUID = -2433655832140195139, local class serialVersionUID = -5449895978211640294
at java.io.ObjectStreamClass.initNonProxy(Unknown Source)
at java.io.ObjectInputStream.readNonProxyDesc(Unknown Source)
at java.io.ObjectInputStream.readClassDesc(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.defaultReadFields(Unknown Source)
at java.io.ObjectInputStream.readSerialData(Unknown Source)
at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source)
at java.io.ObjectInputStream.readObject0(Unknown Source)
at java.io.ObjectInputStream.readObject(Unknown Source)
at sun.rmi.server.UnicastRef.unmarshalValue(Unknown Source)
Now I know that means that the two version of the class are different but I don't see how. The class is only located in one place on the server, so how is it possible that it's different? Any help would be appreciated because I'm at a loss as to what to do or even how to search for the problem.
I have tried to set the UID manually, but that didn't help. I also am using netbeans and deleted the old classfiles to force it to recreate them again and that didn't work either.
I'm using a session bean to put a class in the session. The error is being generated by a class variable that is within the main class to be serialized. Not sure if maybe that has something to do with it.

Answer 1

Now I know that means that the two version of the
class are different but I don't see how.
The class is only located in one place on the server,
so how is it possible that it's different?Did you modify the source file for that class at some point?
Basically, if you never explicitly specified a "serialVersionUID"
in the Java source code, then every time you compile it,
the Java compiler will assign a serialVersionUID for you,
based on the fields you have in your class.
So that's very fragile: if you modify the source file for that class,
then suddenly the UID may change, and you won't be able
to deserialize a object that you previously serialized.
The lesson: for every serializable class,
you should explicitly give it a UID.
It doesn't matter what value you choose. Can be 0.
As long as you choose a value, then the compiler
won't change it back and forth.
As for your particular recovery: it seems you have some
serialized objects that you want to read back.
Did you change the fields between last time and this time?
If you didn't, then just find out what UID value was chosen by the compiler.
Then you write that UID into your source file and recompile.
That should allow you to read-back your old objects.
(But if you've added or removed a field since the last time,
then clearly the default serialization should NOT work.
You would need to read about "readResolve" and
other advanced methods for how to deserialize
an out-of-date file)