title: NotSerializableException when Tomcat startup
body: <p>I'm trying to solve this. I'm using NetBeans 8.0 and TomCat 8.0.9, when server start up throws this NSE:</p>
  
  <pre><code>11-Sep-2014 00:01:43.578 WARNING [http-apr-8080-exec-191] org.apache.catalina.session.StandardSession.doWriteObject No puedo serializar atributo de sesión com.sun.faces.application.view.activeViewMaps para sesión 9AA3A199643F6FDA808F5269DDF0EA86
   java.io.NotSerializableException: model.Estado_civil
  at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1184)
  at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348)
  at java.util.ArrayList.writeObject(ArrayList.java:762)
  at sun.reflect.GeneratedMethodAccessor151.invoke(Unknown Source)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  at java.lang.reflect.Method.invoke(Method.java:483)
  at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:988)
  at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496)
  at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
  at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
  at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548)
  at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509)
  at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
  at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
  at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348)
  at java.util.HashMap.internalWriteEntries(HashMap.java:1777)
  at java.util.HashMap.writeObject(HashMap.java:1354)
  at sun.reflect.GeneratedMethodAccessor239.invoke(Unknown Source)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  at java.lang.reflect.Method.invoke(Method.java:483)
  at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:988)
  at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496)
  at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
  at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
  at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348)
  at java.util.LinkedHashMap.internalWriteEntries(LinkedHashMap.java:333)
  at java.util.HashMap.writeObject(HashMap.java:1354)
  at sun.reflect.GeneratedMethodAccessor239.invoke(Unknown Source)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  at java.lang.reflect.Method.invoke(Method.java:483)
  at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:988)
  at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496)
  at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
  at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
  at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548)
  at java.io.ObjectOutputStream.defaultWriteObject(ObjectOutputStream.java:441)
  at java.util.Collections$SynchronizedMap.writeObject(Collections.java:2691)
  at sun.reflect.GeneratedMethodAccessor1935.invoke(Unknown Source)
  at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
  at java.lang.reflect.Method.invoke(Method.java:483)
  at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:988)
  at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496)
  at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
  at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
  at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348)
  at org.apache.catalina.session.StandardSession.doWriteObject(StandardSession.java:1710)
  at org.apache.catalina.session.StandardSession.writeObjectData(StandardSession.java:1116)
  at org.apache.catalina.session.StandardManager.doUnload(StandardManager.java:401)
  at org.apache.catalina.session.StandardManager.unload(StandardManager.java:320)
  at org.apache.catalina.session.StandardManager.stopInternal(StandardManager.java:487)
  at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:232)
  at org.apache.catalina.core.StandardContext.stopInternal(StandardContext.java:5397)
  at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:232)
  at org.apache.catalina.core.StandardContext.reload(StandardContext.java:3773)
  at org.apache.catalina.manager.ManagerServlet.reload(ManagerServlet.java:984)
  at org.apache.catalina.manager.ManagerServlet.doGet(ManagerServlet.java:345)
  at javax.servlet.http.HttpServlet.service(HttpServlet.java:618)
  at javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
  at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
  at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
  at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
  at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
  at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
  at org.apache.catalina.filters.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:108)
  at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
  at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
  at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
  at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
  at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:615)
  at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:136)
  at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
  at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:610)
  at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
  at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:526)
  at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1078)
  at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:655)
  at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:277)
  at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2381)
  at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2370)
  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
  at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
  at java.lang.Thread.run(Thread.java:745)
  </code></pre>
  
  <p>model.Estado_civil is POJO and isn't referenced. I delete every code could call this POJO I'm using an empty Bean and an empty XHTML.
  I undeployed the project from the server using netbeans and clean and built the project again.
  I can't understand why throws this exception.</p>