@RequestMapping(method = POST, value = "/reg")
    public String registration(@ModelAttribute("userReg") @Valid User user, BindingResult bindingResult,
                               HttpSession session) {
        if(bindingResult.hasErrors()) return "redirect:/reg";
        if (userDAO.findByLogin(user.getLogin()) == null) {
            userDAO.persist(user);
            session.setAttribute("login", user.getLogin());
            return "welcomepage";
        }
        return "Registration";
    }

org.apache.jasper.JasperException: An exception occurred processing JSP page /Registration.jsp at line 18

    15: <form:form action="/reg" method="post" modelAttribute="user">
    16:         <table>
    17:             <tr>
    18:                 <td><form:label path="login">Login:</form:label></td>
    19:                 <td> <form:input path="login"/> </td>
    20:                 <td> <form:errors path="login"/></td>
    21:             </tr>

java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'user' available as request attribute

...<p>
            <tr>
                <td> <form:label  path="password">Password:</form:label></td>
                <td> <form:input  path="password"/> </td>
                <td> <form:errors path="password"/></td>
            </tr>
        <p>
    <input type="submit" value="Registration">
</form:form>

@RequestMapping(method = GET, value = "/reg")
public ModelAndView registration() {
    return new ModelAndView("Registration","user",new User());
}