Spring MVC @ResponseBody returning a Map produces "Error 406 NOT ACCEPTABLE"

You need these two dependencies added in the pom.xml!

<dependency>    <groupId>org.codehaus.jackson</groupId>    <artifactId>jackson-core-lgpl</artifactId>    <version>1.8.1</version></dependency><dependency>    <groupId>org.codehaus.jackson</groupId>    <artifactId>jackson-mapper-lgpl</artifactId>    <version>1.8.1</version></dependency>

I had the same problem and after a couple of hours of debugging I finally found the solution. Just in case someone else get stuck with the same problem, this is what I found.

You probably followed Ajax Simplifications in Spring 3 which tells you to use the mvc:annotation-driven configuration element.

What it doesn't tell you is that mvc:annotation-driven is just a shortcut to define a couple of standard beans, unless you already have one of those beans defined!

With the mvc:annotation-driven configuration a MappingJacksonHttpMessageConverter is registered as a messageConverter on a org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.

If you have defined your own AnnotationMethodHandlerAdapter, you should also manually define this MappingJacksonHttpMessageConverter .

Cfr Custom message converters registered with AnnotationMethodHandlerAdapter are not used, only the default ones are used. which discusses a similar issue.Also check SPR-6524 and SPR-6306, can't post links due to spam prevention :(

The relevant part in my spring config ended up looking like this:

    <bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">        <property name="webBindingInitializer">            <bean class="org.springframework.web.bind.support.ConfigurableWebBindingInitializer">                <property name="validator">                    <bean class="org.springframework.validation.beanvalidation.LocalValidatorFactoryBean">                    </bean>                </property>            </bean>        </property>         <property name="messageConverters">            <list>                   <bean class="org.springframework.http.converter.ByteArrayHttpMessageConverter"/>                <bean class="org.springframework.http.converter.StringHttpMessageConverter"/>                <bean class="org.springframework.http.converter.ResourceHttpMessageConverter"/>                <bean class="org.springframework.http.converter.xml.SourceHttpMessageConverter"/>                <bean class="org.springframework.http.converter.xml.XmlAwareFormHttpMessageConverter"/>                <bean class="org.springframework.http.converter.xml.Jaxb2RootElementHttpMessageConverter"/>                <bean class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter"/>                <bean class="org.springframework.http.converter.feed.AtomFeedHttpMessageConverter"/>                <bean class="org.springframework.http.converter.feed.RssChannelHttpMessageConverter"/>            </list>        </property></bean>

I know this question is a bit old, but I had the same problem.

I solved adding to build path two jars: jackson-core-asl-1.x.jar and jackson-mapper-asl-1.x.jar. You can download them from here: http://wiki.fasterxml.com/JacksonDownload or if you use Maven you can add them as projet dependency.

Note that I used version 1.x (1.9, in my case) and not 2.x. Last version didn't work for me.