We are experiencing intermittent errors during our testing of a pageflow. The stack trace provides little information (that we can use or understand) to help us in identifying the source of this issue. The stack trace does not refer to any code written by us. We are looking for advice on how to resolve this issue. Our environment is JBoss 4.0.5, Seam 1.2, jBPM. We are the error on both Windows and Linux, in both the Sun JVM and JRockit. Any information on the source/resolution of this error would be greatly appreciated. The stack trace that we are seeing: | 2007-04-12 00:27:19,732 ERROR [org.jboss.seam.web.ExceptionFilter] uncaught exception | java.lang.IllegalStateException | at org.apache.catalina.connector.ResponseFacade.sendError(ResponseFacade.java:404) | at javax.servlet.http.HttpServletResponseWrapper.sendError(HttpServletResponseWrapper.java:107) | at org.apache.catalina.servlets.DefaultServlet.serveResource(DefaultServlet.java:698) | at org.apache.catalina.servlets.DefaultServlet.doGet(DefaultServlet.java:354) | at javax.servlet.http.HttpServlet.service(HttpServlet.java:697) | at javax.servlet.http.HttpServlet.service(HttpServlet.java:810) | at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252) | at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173) | at org.jboss.seam.web.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:63) | at org.jboss.seam.debug.hot.HotDeployFilter.doFilter(HotDeployFilter.java:60) | at org.jboss.seam.web.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:49) | at org.jboss.seam.web.RedirectFilter.doFilter(RedirectFilter.java:45) | at org.jboss.seam.web.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:49) | at org.jboss.seam.web.ExceptionFilter.doFilter(ExceptionFilter.java:57) | at org.jboss.seam.web.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:49) | at org.jboss.seam.web.MultipartFilter.doFilter(MultipartFilter.java:79) | at org.jboss.seam.web.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:49) | at org.jboss.seam.web.SeamFilter.doFilter(SeamFilter.java:84) | at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202) | at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173) | at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96) | at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202) | at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173) | at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213) | at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178) | at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:175) | at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:74) | at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126) | at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105) | at org.jboss.web.tomcat.tc5.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:156) | at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107) | at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148) | 2007-04-12 00:27:19,779 ERROR [org.jboss.seam.exceptions.DebugPageHandler] redirecting to debug page | java.lang.IllegalStateException | at org.apache.catalina.connector.ResponseFacade.sendError(ResponseFacade.java:404) | at javax.servlet.http.HttpServletResponseWrapper.sendError(HttpServletResponseWrapper.java:107) | at org.apache.catalina.servlets.DefaultServlet.serveResource(DefaultServlet.java:698) | at org.apache.catalina.servlets.DefaultServlet.doGet(DefaultServlet.java:354) | at javax.servlet.http.HttpServlet.service(HttpServlet.java:697) | at javax.servlet.http.HttpServlet.service(HttpServlet.java:810) | at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:252) | at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173) | at org.jboss.seam.web.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:63) | at org.jboss.seam.debug.hot.HotDeployFilter.doFilter(HotDeployFilter.java:60) | at org.jboss.seam.web.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:49) | at org.jboss.seam.web.RedirectFilter.doFilter(RedirectFilter.java:45) | at org.jboss.seam.web.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:49) | at org.jboss.seam.web.ExceptionFilter.doFilter(ExceptionFilter.java:57) | at org.jboss.seam.web.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:49) | at org.jboss.seam.web.MultipartFilter.doFilter(MultipartFilter.java:79) | at org.jboss.seam.web.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:49) | at org.jboss.seam.web.SeamFilter.doFilter(SeamFilter.java:84) | at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202) | at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173) | at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96) | at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202) | at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173) | at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213) | at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178) | at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:175) | at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:74) | at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126) | at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105) | at org.jboss.web.tomcat.tc5.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:156) | at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107) | at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148) | 2007-04-12 00:27:19,792 ERROR [org.apache.catalina.core.ContainerBase.[jboss.web].[localhost].[/crimnet].[default]] Servlet.service() for servlet default threw exception | java.lang.IllegalArgumentException: Stack must not be null | at org.jboss.seam.core.ConversationEntry.<init>(ConversationEntry.java:40) | at org.jboss.seam.core.ConversationEntries.createConversationEntry(ConversationEntries.java:50) | at org.jboss.seam.core.Manager.createConversationEntry(Manager.java:685) | at org.jboss.seam.core.Manager.beforeRedirect(Manager.java:834) | at org.jboss.seam.core.Manager.beforeRedirect(Manager.java:852) | at org.jboss.seam.exceptions.DebugPageHandler.handle(DebugPageHandler.java:24) | at org.jboss.seam.core.Exceptions.handle(Exceptions.java:79) | at org.jboss.seam.web.ExceptionFilter.endWebRequestAfterException(ExceptionFilter.java:91) | at org.jboss.seam.web.ExceptionFilter.doFilter(ExceptionFilter.java:73) | at org.jboss.seam.web.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:49) | at org.jboss.seam.web.MultipartFilter.doFilter(MultipartFilter.java:79) | at org.jboss.seam.web.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:49) | at org.jboss.seam.web.SeamFilter.doFilter(SeamFilter.java:84) | at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202) | at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173) | at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96) | at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:202) | at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:173) | at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213) | at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:178) | at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:175) | at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:74) | at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:126) | at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105) | at org.jboss.web.tomcat.tc5.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:156) | at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:107) | at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:148) | at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:869) | at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:664) | at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:527) | at org.apache.tomcat.util.net.MasterSlaveWorkerThread.run(MasterSlaveWorkerThread.java:112) | at java.lang.Thread.run(Thread.java:595) | | View the original post : 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