Does anyone know why this happens - here are the circumstances I know this happens under.
There is a main login app, used only for authentication, and lists links to the apps that can be accessed - this has no session timout in the web.xml

Then there are the apps that are specific for different tasks. These have 30min time outs specified in the web.xml.
When there has been no activity on the main app, and after a while someone tries to go back to the main app, this error occurs, & once this occurs all other apps are invalidated, and for now the only thing I can do is re-deploy them all. Pl. advise.

--- Here's the actual error msg ---
org.apache.jasper.JasperException: PutTag.doEndTag(): No InsertTag ancestor
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java(Compiled Code))
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java(Compiled Code))
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java(Compiled Code))
at javax.servlet.http.HttpServlet.service(HttpServlet.java(Compiled Code))
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:256)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java(Compiled Code))
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java(Compiled Code))
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java(Compiled Code))
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java(Compiled Code))
at org.jboss.web.tomcat.security.JBossSecurityMgrRealm.invoke(JBossSecurityMgrRealm.java:220)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java(Compiled Code))
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java(Compiled Code))
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java(Compiled Code))
at org.apache.catalina.valves.CertificatesValve.invoke(CertificatesValve.java(Compiled Code))
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java(Compiled Code))
at org.jboss.web.tomcat.tc4.statistics.ContainerStatsValve.invoke(ContainerStatsValve.java(Compiled Code))
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java(Compiled Code))
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java(Compiled Code))
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java(Inlined Compiled Code))
at org.apache.catalina.core.StandardContext.invoke(StandardContext.java(Compiled Code))
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java(Compiled Code))
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java(Compiled Code))
at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java(Compiled Code))
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java(Compiled Code))
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java(Compiled Code))
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java(Compiled Code))
at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java(Compiled Code))
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java(Compiled Code))
at org.jboss.web.tomcat.tc4.authenticator.SingleSignOn.invoke(SingleSignOn.java(Compiled Code))
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java(Compiled Code))
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java(Compiled Code))
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java(Compiled Code))
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java(Compiled Code))
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java(Compiled Code))
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java(Compiled Code))
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java(Compiled Code))
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java(Compiled Code))
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java(Compiled Code))
at org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java(Compiled Code))
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java(Compiled Code))
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java(Compiled Code))
at org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java(Compiled Code))
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:677)
at java.lang.Thread.run(Thread.java:568)

root cause

javax.servlet.ServletException: PutTag.doEndTag(): No InsertTag ancestor
at org.apache.jasper.runtime.PageContextImpl.handlePageException(PageContextImpl.java:533)
at org.apache.jsp.main_jsp._jspService(main_jsp.java:69)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java(Compiled Code))
at javax.servlet.http.HttpServlet.service(HttpServlet.java(Compiled Code))
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java(Compiled Code))
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java(Compiled Code))
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java(Compiled Code))
at javax.servlet.http.HttpServlet.service(HttpServlet.java(Compiled Code))
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:256)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java(Compiled Code))
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java(Compiled Code))
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java(Compiled Code))
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java(Compiled Code))
at org.jboss.web.tomcat.security.JBossSecurityMgrRealm.invoke(JBossSecurityMgrRealm.java:220)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java(Compiled Code))
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java(Compiled Code))
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java(Compiled Code))
at org.apache.catalina.valves.CertificatesValve.invoke(CertificatesValve.java(Compiled Code))
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java(Compiled Code))
at org.jboss.web.tomcat.tc4.statistics.ContainerStatsValve.invoke(ContainerStatsValve.java(Compiled Code))
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java(Compiled Code))
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java(Compiled Code))
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java(Inlined Compiled Code))
at org.apache.catalina.core.StandardContext.invoke(StandardContext.java(Compiled Code))
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java(Compiled Code))
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java(Compiled Code))
at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java(Compiled Code))
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java(Compiled Code))
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java(Compiled Code))
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java(Compiled Code))
at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java(Compiled Code))
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java(Compiled Code))
at org.jboss.web.tomcat.tc4.authenticator.SingleSignOn.invoke(SingleSignOn.java(Compiled Code))
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java(Compiled Code))
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java(Compiled Code))
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java(Compiled Code))
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java(Compiled Code))
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java(Compiled Code))
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java(Compiled Code))
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java(Compiled Code))
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java(Compiled Code))
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java(Compiled Code))
at org.apache.coyote.tomcat4.CoyoteAdapter.service(CoyoteAdapter.java(Compiled Code))
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java(Compiled Code))
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java(Compiled Code))
at org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java(Compiled Code))
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:677)
at java.lang.Thread.run(Thread.java:568)