HTTP Status 500

[cyberusa]

請問一下各位
在執行部分指令時會出現以下訊息
但不知是哪裡有問題，可否請各位指教一下!?
type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.
exception
javax.servlet.ServletException: java.lang.NumberFormatException: null
org.apache.struts.action.RequestProcessor.processException(RequestProcessor.java:495)
org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:436)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:266)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1219)
org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:481)
com.rl.standard.servlet.GBKActionComponentServlet.doGet(GBKActionComponentServlet.java:17)
javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
com.gs.standard.util.FilterC.doFilter(FilterC.java:81)
org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
root cause