RulesListener exception raised after trying to restore the previous content

I Created a content object by adding a title and body , reopened the update content object engine and edited it by modifying the body, reopened again the update content object engine and clicked on versioning tab and restore the old version, the old content had been restored correctly but Ihad this exception in the console:

2008-12-03 15:47:12,656: ERROR [org.jahia.services.content.automation.RulesListener] - Error when executing event
javax.jcr.PathNotFoundException: mainContentTitle
at org.jahia.services.content.impl.jahia.NodeImpl.getProperty(NodeImpl.java:244)
at org.jahia.services.content.impl.jahia.SessionImpl.getItem(SessionImpl.java:153)
at org.jahia.services.content.automation.RulesListener.onEvent(RulesListener.java:217)
at org.jahia.services.content.impl.jahia.ObservationManagerImpl.callListeners(ObservationManagerImpl.java:228)
at org.jahia.services.content.impl.jahia.ObservationManagerImpl.fire(ObservationManagerImpl.java:168)
at org.jahia.services.content.impl.jahia.ObservationManagerImpl.fireEvents(ObservationManagerImpl.java:70)
at org.jahia.services.content.impl.jahia.JCRListener.aggregatedObjectChanged(JCRListener.java:43)
at sun.reflect.GeneratedMethodAccessor780.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.jahia.registries.JahiaListenersRegistry.wakeupListeners(JahiaListenersRegistry.java:173)
at org.jahia.services.events.JahiaEventGeneratorBaseService.fireAggregatedEvents(JahiaEventGeneratorBaseService.java:121)
at org.jahia.services.events.JahiaEventGeneratorBaseService$$FastClassByCGLIB$$15089916.invoke(<generated>)
at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:149)
at org.springframework.aop.framework.Cglib2AopProxy$CglibMethodInvocation.invokeJoinpoint(Cglib2AopProxy.java:700)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:149)
at org.springframework.aop.interceptor.AbstractTraceInterceptor.invoke(AbstractTraceInterceptor.java:113)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:635)
at org.jahia.services.events.JahiaEventGeneratorBaseService$$EnhancerByCGLIB$$25db4cf9.fireAggregatedEvents(<generated>)
at org.jahia.views.engines.versioning.actions.ContentVersioningAction.restoreContainerSave(ContentVersioningAction.java:924)
at org.jahia.views.engines.versioning.actions.ContentVersioningAction.restoreSave(ContentVersioningAction.java:728)
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 org.apache.struts.actions.DispatchAction.dispatchMethod(DispatchAction.java:270)
at org.apache.struts.actions.DispatchAction.execute(DispatchAction.java:187)
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:431)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:236)
at org.jahia.bin.JahiaRequestProcessor.process(JahiaRequestProcessor.java:82)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
at org.jahia.bin.Jahia.process(Jahia.java:1557)
at org.jahia.bin.Jahia.service(Jahia.java:851)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.jahia.bin.filters.jcr.JcrSessionFilter.doFilter(JcrSessionFilter.java:23)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.tuckey.web.filters.urlrewrite.RuleChain.handleRewrite(RuleChain.java:164)
at org.tuckey.web.filters.urlrewrite.RuleChain.doRules(RuleChain.java:141)
at org.tuckey.web.filters.urlrewrite.UrlRewriter.processRequest(UrlRewriter.java:90)
at org.tuckey.web.filters.urlrewrite.UrlRewriteFilter.doFilter(UrlRewriteFilter.java:417)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.jahia.bin.filters.ResponseCacheControlFilter.doFilter(ResponseCacheControlFilter.java:94)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:433)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:568)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:845)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
at java.lang.Thread.run(Thread.java:595)