Ayuda con error (HTTP Status 500)

[knhoteles]

Como puedo hacer para corregir este error.

HTTP Status 500 -
________________________________________
type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.
exception
javax.servlet.ServletException: java.lang.NullPointerException
org.apache.struts.action.RequestProcessor.processE xception(RequestProcessor.java:535)
org.apache.struts.action.RequestProcessor.processA ctionPerform(RequestProcessor.java:433)
org.apache.struts.action.RequestProcessor.process( RequestProcessor.java:236)
org.apache.struts.action.ActionServlet.process(Act ionServlet.java:1196)
org.apache.struts.action.ActionServlet.doPost(Acti onServlet.java:432)
javax.servlet.http.HttpServlet.service(HttpServlet .java:637)
javax.servlet.http.HttpServlet.service(HttpServlet .java:717)
org.jboss.web.tomcat.filters.ReplyHeaderFilter.doF ilter(ReplyHeaderFilter.java:96)
root cause
java.lang.NullPointerException
note The full stack trace of the root cause is available in the JBossWeb/2.0.0.GA_CP logs.
________________________________________
JBossWeb/2.0.0.GA_CP

Muchas gracias.