请帮我看看这个异常是由于什么原因造成的？

Question

at com.ibm.ws.jsp.runtime.HttpJspBase.service(HttpJspBase.java:91)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java(Compiled Code))
at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1521)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java(Compiled Code))
at com.ibm.ws.webcontainer.filter.WebAppFilterChain._doFilter(WebAppFilterChain.java(Compiled Code))
at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java(Compiled Code))
at com.ibm.wsspi.webcontainer.servlet.GenericServletWrapper.handleRequest(GenericServletWrapper.java:121)
at com.ibm.ws.jsp.webcontainerext.JSPExtensionServletWrapper.handleRequest(JSPExtensionServletWrapper.java:204)
at com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcher.include(WebAppRequestDispatcher.java:633)
at com.ibm.wps.services.dispatcher.DispatcherServiceImpl.handleRequest(DispatcherServiceImpl.java:87)
at com.ibm.wps.services.dispatcher.DispatcherServiceImpl.include(DispatcherServiceImpl.java:52)
at com.ibm.wps.services.dispatcher.Dispatcher.include(Dispatcher.java:45)
at com.ibm.wps.engine.templates.skins.Default.render(Default.java:115)
at com.ibm.wps.engine.templates.SkinTemplate.render(SkinTemplate.java:71)
at com.ibm.wps.composition.elements.Component.render(Component.java:845)
at com.ibm.wps.composition.Composition.render(Composition.java:2568)
at com.ibm.websphere.personalization.transformation.PznTransformationLayoutModel.render(PznTransformationLayoutModel.java:70)
at com.ibm.wps.model.wrappers.LayoutModelWrapperFactoryImpl$LayoutModelWrapperImpl.render(LayoutModelWrapperFactoryImpl.java:218)
at com.ibm.wps.engine.tags2.PageRenderTag.doStartTag(PageRenderTag.java:396)
at com.ibm._jsp._Home._jspService(_Home.java:82)
at com.ibm.ws.jsp.runtime.HttpJspBase.service(HttpJspBase.java:91)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java(Compiled Code))
at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1521)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java(Compiled Code))
at com.ibm.ws.webcontainer.filter.WebAppFilterChain._doFilter(WebAppFilterChain.java(Compiled Code))
at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java(Compiled Code))
at com.ibm.wsspi.webcontainer.servlet.GenericServletWrapper.handleRequest(GenericServletWrapper.java:121)
at com.ibm.ws.jsp.webcontainerext.JSPExtensionServletWrapper.handleRequest(JSPExtensionServletWrapper.java:204)
at com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcher.include(WebAppRequestDispatcher.java:633)
at com.ibm.wps.services.dispatcher.DispatcherServiceImpl.handleRequest(DispatcherServiceImpl.java:87)
at com.ibm.wps.services.dispatcher.DispatcherServiceImpl.include(DispatcherServiceImpl.java:52)
at com.ibm.wps.services.dispatcher.Dispatcher.include(Dispatcher.java:54)
at com.ibm.wps.engine.templates.screens.Default.render(Default.java:91)
at com.ibm.wps.engine.templates.ScreenTemplate.render(ScreenTemplate.java(Compiled Code))
at com.ibm.wps.engine.tags2.ScreenRenderTag.doStartTag(ScreenRenderTag.java(Compiled Code))
at com.ibm._jsp._Default._jspx_meth_portal$1core_screenRender_0(_Default.java:4665)
at com.ibm._jsp._Default._jspService(_Default.java:2410)
at com.ibm.ws.jsp.runtime.HttpJspBase.service(HttpJspBase.java:91)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java(Compiled Code))
at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1521)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java(Compiled Code))
at com.ibm.ws.webcontainer.filter.WebAppFilterChain._doFilter(WebAppFilterChain.java(Compiled Code))
at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java(Compiled Code))
at com.ibm.wsspi.webcontainer.servlet.GenericServletWrapper.handleRequest(GenericServletWrapper.java:121)
at com.ibm.ws.jsp.webcontainerext.JSPExtensionServletWrapper.handleRequest(JSPExtensionServletWrapper.java:204)
at com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcher.include(WebAppRequestDispatcher.java:633)
at com.ibm.wps.services.dispatcher.DispatcherServiceImpl.handleRequest(DispatcherServiceImpl.java:87)
at com.ibm.wps.services.dispatcher.DispatcherServiceImpl.include(DispatcherServiceImpl.java:52)
at com.ibm.wps.services.dispatcher.Dispatcher.include(Dispatcher.java:45)
at com.ibm.wps.engine.templates.themes.Default.render(Default.java:142)
at com.ibm.wps.engine.templates.ThemeTemplate.render(ThemeTemplate.java:67)
at com.ibm.wps.engine.phases.WPRenderPhase.processRendering(WPRenderPhase.java:322)
at com.ibm.wps.engine.phases.WPRenderPhase.execute(WPRenderPhase.java:137)
at com.ibm.wps.state.phases.AbstractRenderPhase.next(AbstractRenderPhase.java:106)
at com.ibm.wps.engine.phases.WPAbstractRenderPhase.next(WPAbstractRenderPhase.java:93)
at com.ibm.wps.engine.Servlet.callPortal(Servlet.java:791)
at com.ibm.wps.engine.Servlet.doGet(Servlet.java:629)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:743)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java(Compiled Code))
at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1521)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java(Compiled Code))
at com.ibm.wps.state.filter.StateCleanup.doFilter(StateCleanup.java:86)
at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java(Compiled Code))
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java(Compiled Code))
at com.ibm.wps.mappingurl.impl.URLAnalyzer.doFilter(URLAnalyzer.java:257)
at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java(Compiled Code))
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java(Compiled Code))
at com.ibm.ws.webcontainer.filter.WebAppFilterChain._doFilter(WebAppFilterChain.java(Compiled Code))
at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java(Compiled Code))
at com.ibm.ws.webcontainer.webapp.WebApp.handleRequest(WebApp.java:3146)
at com.ibm.ws.webcontainer.webapp.WebGroup.handleRequest(WebGroup.java:250)
at com.ibm.ws.webcontainer.VirtualHost.handleRequest(VirtualHost.java:212)
at com.ibm.ws.webcontainer.WebContainer.handleRequest(WebContainer.java:1958)
at com.ibm.ws.webcontainer.channel.WCChannelLink.ready(WCChannelLink.java:112)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleDiscrimination(HttpInboundLink.java:472)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleNewInformation(HttpInboundLink.java:411)
at com.ibm.ws.http.channel.inbound.impl.HttpICLReadCallback.complete(HttpICLReadCallback.java:101)
at com.ibm.ws.tcp.channel.impl.WorkQueueManager.requestComplete(WorkQueueManager.java(Compiled Code))
at com.ibm.ws.tcp.channel.impl.WorkQueueManager.attemptIO(WorkQueueManager.java(Compiled Code))
at com.ibm.ws.tcp.channel.impl.WorkQueueManager.workerRun(WorkQueueManager.java:952)
at com.ibm.ws.tcp.channel.impl.WorkQueueManager$Worker.run(WorkQueueManager.java:1039)
at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java(Compiled Code))谢谢！