500 Internal Server Error

java.lang.NullPointerException
at instore.content.RepositoryView.createAtNode(RepositoryView.java:178)
at instore.content.view.Site.getSite(Site.java:65)
at instore.content.view.struts.NavigateAction.execute(NavigateAction.java:52)
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:419)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:224)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:740)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at com.evermind[Oracle Application Server Containers for J2EE 10g (10.1.2.0.2)].server.http.ResourceFilterChain.doFilter(ResourceFilterChain.java:65)
at oracle.security.jazn.oc4j.JAZNFilter.doFilter(Unknown Source)
at com.evermind[Oracle Application Server Containers for J2EE 10g (10.1.2.0.2)].server.http.EvermindFilterChain.doFilter(EvermindFilterChain.java:16)
at instore.hibernate.HibernateSessionFilter.doFilter(HibernateSessionFilter.java:24)
at com.evermind[Oracle Application Server Containers for J2EE 10g (10.1.2.0.2)].server.http.EvermindFilterChain.doFilter(EvermindFilterChain.java:20)
at instore.waf.utils.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:170)
at com.evermind[Oracle Application Server Containers for J2EE 10g (10.1.2.0.2)].server.http.ServletRequestDispatcher.invoke(ServletRequestDispatcher.java:659)
at com.evermind[Oracle Application Server Containers for J2EE 10g (10.1.2.0.2)].server.http.ServletRequestDispatcher.forwardInternal(ServletRequestDispatcher.java:330)
at com.evermind[Oracle Application Server Containers for J2EE 10g (10.1.2.0.2)].server.http.HttpRequestHandler.processRequest(HttpRequestHandler.java:830)
at com.evermind[Oracle Application Server Containers for J2EE 10g (10.1.2.0.2)].server.http.AJPRequestHandler.run(AJPRequestHandler.java:224)
at com.evermind[Oracle Application Server Containers for J2EE 10g (10.1.2.0.2)].server.http.AJPRequestHandler.run(AJPRequestHandler.java:133)
at com.evermind[Oracle Application Server Containers for J2EE 10g (10.1.2.0.2)].util.ReleasableResourcePooledExecutor$MyWorker.run(ReleasableResourcePooledExecutor.java:192)
at java.lang.Thread.run(Thread.java:534)