Hi, I've just uploaded a very simple web app that uses hibernate via a war file to my webserver:
http://www.colin-java.co.uk/BANK
The first couple of times I loaded the page above, it was fine, and it correctly displayed some of the contents of the User (MySQL) table.

But now when I load it, I get this error...

HTTP Status 500 -

exception

org.apache.jasper.JasperException: An exception occurred processing JSP page /index.jsp at line 25

null

Stacktrace:
	org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:510)
	org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:419)
	org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
	org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
	sun.reflect.GeneratedMethodAccessor6469.invoke(Unknown Source)
	sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	java.lang.reflect.Method.invoke(Method.java:597)
	org.apache.catalina.security.SecurityUtil$1.run(SecurityUtil.java:269)
	java.security.AccessController.doPrivileged(Native Method)
	javax.security.auth.Subject.doAsPrivileged(Subject.java:517)
	org.apache.catalina.security.SecurityUtil.execute(SecurityUtil.java:301)
	org.apache.catalina.security.SecurityUtil.doAsPrivilege(SecurityUtil.java:162)
root cause

java.lang.NullPointerException
	org.apache.jsp.index_jsp._jspService(index_jsp.java:77)
	org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
	org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:377)
	org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)
	org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
	sun.reflect.GeneratedMethodAccessor6469.invoke(Unknown Source)
	sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	java.lang.reflect.Method.invoke(Method.java:597)
	org.apache.catalina.security.SecurityUtil$1.run(SecurityUtil.java:269)
	java.security.AccessController.doPrivileged(Native Method)
	javax.security.auth.Subject.doAsPrivileged(Subject.java:517)
	org.apache.catalina.security.SecurityUtil.execute(SecurityUtil.java:301)
	org.apache.catalina.security.SecurityUtil.doAsPrivilege(SecurityUtil.java:162)

The index.jsp page is shown below:

<%@page import="bank.User"%>
<%@page import="java.util.List"%>
<%@page import="bank.BankHelper"%>
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
   "http://www.w3.org/TR/html4/loose.dtd">

<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>JSP Page</title>
    </head>
    <body>
        <h1>Hello World!</h1>
        <%
        BankHelper helper = new BankHelper();
        List<User> users = helper.getUsers();

        for(User user : users)            //  **********  LINE 25 ************
        {
            out.println("user is "+user.getSurname()+"<BR>");
        }
        %>
    </body>
</html>

So it appears that 'users' on line 23 is null.

If I display the BankHelper class to look at the getUsers method,
perhaps this is the problem.

package bank;

import java.util.List;
import org.hibernate.Query;
import org.hibernate.Session;

public class BankHelper
{

    Session session = null;

    public BankHelper()
    {
        this.session = HibernateUtil.getSessionFactory().getCurrentSession();
    }

    public List<User> getUsers()
    {
        List<User> users = null;

        try
        {
            org.hibernate.Transaction tx = session.beginTransaction();
            Query q = session.createQuery("from User as user");
            users = q.list();
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }

        return users;
    }
}

Can anyone help figure out what I'm doing wrong, I don't like it when things work first time, but not after.
Any help is much appreciated. Thanks

The NullPointerException could mean that something is null at that line. Can you try this small debug code:

<%@page import="bank.User"%>
<%@page import="java.util.List"%>
<%@page import="bank.BankHelper"%>
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
   "http://www.w3.org/TR/html4/loose.dtd">

<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>JSP Page</title>
    </head>
    <body>
        <h1>Hello World!</h1>
        <%
        BankHelper helper = new BankHelper();
        List<User> users = helper.getUsers();

        System.out.println(users); // this prints at the server not the web page

        if (users!=null) {
          for(User user : users)            
          {
        %>
             user is <%=user.getSurname()%>
             <BR>
        <%
          }
        } else {
        %>
           users is NULL!
        <%
        }
        %>
    </body>
</html>

If you still get errors post them as well the updated line where they occur