spring 4 ajax response in 406 not acceptable

Question

Application is developed using Spring MVC 4, Hibernate, and jQuery

Below jquery AJAX call is not giving proper response..it is saying 406 error (not acceptable)

I know it is very old and common problem. I have tried:

1. jackson jars
2. in RequestMapping annotation : producers as JSON
3. in RequestMapping annotation : Header as JSON
4. combination of 2 and 3
5. $.post instead of $.ajax (i know it doesn't make difference)
6. My bean object(ValidationResponse) has proper setters and getters
7. URL doesn't have .htm
8. adding accept JSON header like accept: { json: 'application/json', xml: 'application/xml' },

jQuery Call in JSP

 $.ajax({
                url: "register",    
                data: $('#regForm').serialize(), 
                type: "POST",
                 accept: {
                  json: 'application/json',
                  xml: 'application/xml'
            },
                success: function(result) {  
                // success message
                },
                error: function(XMLHttpRequest, textStatus, errorThrown){
                    alert(XMLHttpRequest.toString());

                }
            });

My Controller

LoginController

@RequestMapping(value="/register", 
            method   = RequestMethod.POST)
    public @ResponseBody 
    ValidationResponse register(@Valid @ModelAttribute("user") User user, BindingResult result, ModelMap map) {
        ValidationResponse res = new ValidationResponse();

        // Saving into DB logic
        return res; // till here I can see all the values correctly while debugging
    }

ValidationResponse bean

public class ValidationResponse {

    private String status;
    private ErrorMessage[] errorMessageList;

//getter and setter
}

Errormessage bean

public class ErrorMessage {

    private String fieldName;
    private String message;
//getter and setters
}

app-servlet.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xsi:schemaLocation="
                        http://www.springframework.org/schema/beans
                        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
                        http://www.springframework.org/schema/context
                        http://www.springframework.org/schema/context/spring-context-3.0.xsd
                        http://www.springframework.org/schema/mvc
                        http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd 
                        http://www.springframework.org/schema/tx
                        http://www.springframework.org/schema/tx/spring-tx-4.1.xsd">

    <mvc:annotation-driven />
    <mvc:resources mapping="/assets/**" location="/assets/"  />

    <context:property-placeholder location="classpath:database.properties" />
    <context:component-scan base-package="com.app" />

    <tx:annotation-driven transaction-manager="hibernateTransactionManager"/>

    <bean id="jspViewResolver"
        class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="viewClass"
            value="org.springframework.web.servlet.view.JstlView" />
        <property name="prefix" value="/WEB-INF/views/" />
        <property name="suffix" value=".jsp" />
    </bean>

    <bean id="dataSource"
        class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="${database.driver}" />
        <property name="url" value="${database.url}" />
        <property name="username" value="${database.user}" />
        <property name="password" value="${database.password}" />
    </bean>

    <bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <property name="hibernateProperties">
            <props>
                <prop key="hibernate.dialect">${hibernate.dialect}</prop>
                <prop key="hibernate.show_sql">${hibernate.show_sql}</prop>
                <prop key="hibernate.hbm2ddl.auto">${hibernate.hbm2ddl.auto}</prop> 
            </props>
        </property>
        <property name="packagesToScan" value="com.app"></property>
    </bean>

    <!-- bind your messages.properties -->
    <bean class="org.springframework.context.support.ResourceBundleMessageSource"
        id="messageSource">
        <property name="basename" value="messages" />
    </bean>

</beans>

Response header

HTTP/1.1 406 Not Acceptable
Server: Apache-Coyote/1.1
Content-Type: text/html;charset=utf-8
Content-Length: 1074
Date: Mon, 16 Mar 2015 03:56:02 GMT

Request Header

POST /app/register HTTP/1.1
Host: localhost:8080
Connection: keep-alive
Content-Length: 104
Accept: text/json; text/html; charset=utf-8
Origin: http://localhost:8080
X-Requested-With: XMLHttpRequest
User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2272.89 Safari/537.36
Content-Type: text/json; text/html; charset=UTF-8
Referer: http://localhost:8080/app/home
Accept-Encoding: gzip, deflate
Accept-Language: en-US,en;q=0.8

Let me know if you need any other detail.

Answer 1

Add the following dependencies

<dependency>
  <groupId>com.fasterxml.jackson.core</groupId>
  <artifactId>jackson-core</artifactId>
  <version>2.5.1</version>
</dependency>
<dependency>
  <groupId>com.fasterxml.jackson.core</groupId>
  <artifactId>jackson-databind</artifactId>
  <version>2.5.1</version> 
</dependency>
<dependency>
  <groupId>com.fasterxml.jackson.core</groupId>
  <artifactId>jackson-annotations</artifactId>
  <version>2.5.1</version>
</dependency>