406 response code when sending JSON

With bad configured Spring message converters, you won't able to handle JSON code. If you receive a response with 406 code when you try to send JSON, a problem with message converters can be the reason of this error. First, you should check your configuration file and see if inside <mvc:annotation-driven /> you put:
  <bean class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter"/>
The second check should be made at classpath level. Here, you should verify if the JAR with converter used to JSON format is present. In this case, we need to look for JARs of Jackson library.