java.lang.NullPointerException
   org.hibernate.cache.impl.bridge.RegionFactoryCacheProviderBridge.nextTimestamp(RegionFactoryCacheProviderBridge.java:93)
   org.hibernate.impl.SessionFactoryImpl.openSession(SessionFactoryImpl.java:639)
   org.hibernate.impl.SessionFactoryImpl.openSession(SessionFactoryImpl.java:648)
   com.package1.service.AuthenticateUser.addUser(AuthenticateUser.java:32)
   com.package1.controllers.LoginServlet.doPost(LoginServlet.java:68)

public class LoginServlet extends HttpServlet {
   private static final long serialVersionUID = 1L;
   protected void doPost(HttpServletRequest request,
         HttpServletResponse response) throws ServletException, IOException {
      PrintWriter out = response.getWriter();
      String username = request.getParameter("user");
      String password = request.getParameter("pass");

      response.setContentType("text/html");
      String result = authenticateUser.authenticateUser(username, password);

      if (result == "SUCCESS") {
         RequestDispatcher rqdpr = request.getRequestDispatcher("Success.jsp");
         rqdpr.forward(request, response);
      }else {
         //response.sendRedirect("Register.jsp");
         authenticateUser.addUser("abcdef", "abcdef","abcdef", "abcdef");   //Line: 68
      }
      
      
   }
   
   private AuthenticateUser authenticateUser = new AuthenticateUser();
}

public class AuthenticateUser {

   public String authenticateUser(String username, String password) {
      Session session = factory.openSession();
      Transaction txn = session.getTransaction();
      String usernamefromdb = user.getName();
      String passwordfromdb = user.getPassword();

      try {
         if (username.equals(usernamefromdb)
               && password.equals(passwordfromdb)) {
            return "SUCCESS";
         } else {
            return "FAILURE";
         }
      } finally {
         factory.close();
      }
   }

   public void addUser(String uname, String uemail, String usrnme,
         String upass) {
      Session session = factory.openSession();                       // Line 32
      Transaction txn = session.beginTransaction();
      user.setName(uname);
      user.setEmail(uemail);
      user.setUsrname(usrnme);
      user.setPassword(upass);
      txn.commit();
      session.save(user);
      session.close();
      factory.close();
   }

   private static SessionFactory factory = HibernateSessionManager
         .getSessionFactory();
   private User user = new User();
}

<property name="hibernate.cache.use_second_level_cache">true</property>

<property name="hibernate.cache.region.factory_class">net.sf.ehcache.hibernate.EhCacheRegionFactory</property>

public class AuthenticateUser {

   public String authenticateUser(String username, String password) {
      
      return "ABC";
   }

   public void addUser(String uname, String uemail, String usrnme,
         String upass) {
      Session session = factory.openSession();
      Transaction txn = session.beginTransaction();
      user.setId(1);
      user.setName(uname);
      user.setEmail(uemail);
      user.setUsrname(usrnme);
      user.setPassword(upass);
      txn.commit();
      session.save(user);
      session.close();
      factory.close();
   }

   private static SessionFactory factory = HibernateSessionManager
         .getSessionFactory();
   private User user = new User();
}

<hibernate-configuration>

     <session-factory>

        <!-- Database connection settings -->
        <property name="connection.driver_class">org.postgresql.Driver</property>
        <property name="connection.url">jdbc:postgresql://localhost:5432/hibernatedb</property>
        <property name="connection.username">postgres</property>
        <property name="connection.password">admin</property>

        <!-- JDBC connection pool (use the built-in) -->
        <property name="connection.pool_size">1</property>

        <!-- SQL dialect -->
        <property name="dialect">org.hibernate.dialect.PostgreSQLDialect</property>

        <!-- Disable the second-level cache  -->
        <property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>

        <!-- Echo all executed SQL to stdout -->
        <property name="show_sql">true</property>

        <!-- Drop and re-create the database schema on startup -->
        <property name="hbm2ddl.auto">Update</property>

        <!-- Names the annotated entity class -->
        <mapping class="com.package1.model.User"/>

    </session-factory>
</hibernate-configuration>

<property name="hbm2ddl.auto">Update</property>

<property name="hbm2ddl.auto">update</property>

<property name="hbm2ddl.auto">create-drop</property>