HTTP Status 500 -type Exception reportmessagedescription The server encountered an internal error () that prevented it from fulfilling this request.exceptionorg.apache.jasper.JasperException org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:358) org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:301) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:248) javax.servlet.http.HttpServlet.service(HttpServlet.java:810) org.apache.struts.action.RequestProcessor.doForward(RequestProcessor.java:1097) org.apache.struts.action.RequestProcessor.processForwardConfig(RequestProcessor.java:429) org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:272) org.apache.struts.action.ActionServlet.process(ActionServlet.java:1187) org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:451) javax.servlet.http.HttpServlet.service(HttpServlet.java:717) javax.servlet.http.HttpServlet.service(HttpServlet.java:810) com.ctdw.zk.filter.FunctionFilterSession.doFilter(Unknown Source) com.ctdw.zk.filter.WpStudentFilter.doFilter(Unknown Source) com.ctdw.zk.filter.student.ExamStopOrStartStudentFilter.doFilter(Unknown Source) com.ctdw.base.filters.RequestEncodingFilter.doFilter(Unknown Source)root causejava.lang.NullPointerException org.apache.jsp.login.jbxx_jsp._jspService(jbxx_jsp.java:260) org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:133) javax.servlet.http.HttpServlet.service(HttpServlet.java:810) org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:311) org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:301) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:248) javax.servlet.http.HttpServlet.service(HttpServlet.java:810) org.apache.struts.action.RequestProcessor.doForward(RequestProcessor.java:1097) org.apache.struts.action.RequestProcessor.processForwardConfig(RequestProcessor.java:429) org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:272) org.apache.struts.action.ActionServlet.process(ActionServlet.java:1187) org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:451) javax.servlet.http.HttpServlet.service(HttpServlet.java:717) javax.servlet.http.HttpServlet.service(HttpServlet.java:810) com.ctdw.zk.filter.FunctionFilterSession.doFilter(Unknown Source) com.ctdw.zk.filter.WpStudentFilter.doFilter(Unknown Source) com.ctdw.zk.filter.student.ExamStopOrStartStudentFilter.doFilter(Unknown Source) com.ctdw.base.filters.RequestEncodingFilter.doFilter(Unknown Source)note The full stack trace of the root cause is available in the Tomcat logs.Apache Tomcat/5.0.19