I have configured all the OpenNms to monitor the services, but when configuring the custom notifications.
At the final step of creating through the jetty web- admin- configure notification- configure notage path- adding email- and finish. At the last step i got this error with the follwing tracking notice..

The OpenNMS web UI has encountered an error that it does not know how to handle.

Possible causes could be that the database is not responding, the OpenNMS application has stopped or is not running, or there is an issue with the servlet container.

Please bring this message to the attention of the person responsible for maintaining OpenNMS for your organization, and have him or her check that OpenNMS, the external servlet container (if applicable), and the database are all running without errors.

To reveal details of the error encountered and instructions for reporting it, click here.

org.exolab.castor.xml.ValidationException
at org.exolab.castor.xml.FieldValidator.validate(FieldValidator.java:277)
at org.exolab.castor.xml.util.XMLClassDescriptorImpl.validate(XMLClassDescriptorImpl.java:1048)
at org.exolab.castor.xml.Validator.validate(Validator.java:127)
at org.exolab.castor.xml.FieldValidator.validate(FieldValidator.java:244)
at org.exolab.castor.xml.util.XMLClassDescriptorImpl.validate(XMLClassDescriptorImpl.java:1048)
at org.exolab.castor.xml.Validator.validate(Validator.java:127)
at org.exolab.castor.xml.Marshaller.validate(Marshaller.java:2527)
at org.exolab.castor.xml.Marshaller.marshal(Marshaller.java:824)
at org.exolab.castor.xml.Marshaller.marshal(Marshaller.java:730)
at org.opennms.netmgt.config.DestinationPathManager.saveCurrent(DestinationPathManager.java:306)
at org.opennms.netmgt.config.DestinationPathManager.addPath(DestinationPathManager.java:233)
at org.opennms.web.admin.notification.DestinationWizardServlet.doPost(DestinationWizardServlet.java:174)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
at org.extremecomponents.table.filter.AbstractExportFilter.doFilter(AbstractExportFilter.java:49)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.opennms.web.StoreRequestPropertiesFilter.doFilter(StoreRequestPropertiesFilter.java:80)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:378)
at org.opennms.web.springframework.security.AuthFilterEnabler.doFilterHttp(AuthFilterEnabler.java:110)
at org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53)
at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:390)
at org.springframework.security.intercept.web.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:109)
at org.springframework.security.intercept.web.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:83)
at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:390)
at org.springframework.security.ui.SessionFixationProtectionFilter.doFilterHttp(SessionFixationProtectionFilter.java:67)
at org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53)
at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:390)
at org.springframework.security.ui.ExceptionTranslationFilter.doFilterHttp(ExceptionTranslationFilter.java:101)
at org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53)
at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:390)
at org.springframework.security.providers.anonymous.AnonymousProcessingFilter.doFilterHttp(AnonymousProcessingFilter.java:105)
at org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53)
at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:390)
at org.springframework.security.wrapper.SecurityContextHolderAwareRequestFilter.doFilterHttp(SecurityContextHolderAwareRequestFilter.java:91)
at org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53)
at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:390)
at org.springframework.security.ui.basicauth.BasicProcessingFilter.doFilterHttp(BasicProcessingFilter.java:174)
at org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53)
at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:390)
at org.springframework.security.ui.AbstractProcessingFilter.doFilterHttp(AbstractProcessingFilter.java:278)
at org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53)
at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:390)
at org.springframework.security.ui.logout.LogoutFilter.doFilterHttp(LogoutFilter.java:89)
at org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53)
at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:390)
at org.springframework.security.context.HttpSessionContextIntegrationFilter.doFilterHttp(HttpSessionContextIntegrationFilter.java:235)
at org.springframework.security.ui.SpringSecurityFilter.doFilter(SpringSecurityFilter.java:53)
at org.springframework.security.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:390)
at org.springframework.security.util.FilterChainProxy.doFilter(FilterChainProxy.java:175)
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:237)
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:167)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:198)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
at org.mortbay.jetty.handler.HandlerCollection.handle(HandlerCollection.java:114)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:326)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:943)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:756)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:212)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:410)
at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)