Today we’ve got such exception
org.springframework.web.HttpMediaTypeNotAcceptableException: Could not find acceptable representation
quick investigation on Spring sources led us to issue with json serialization.
We use jackson for converting from object to json behind the scene
For Spring 3.x we configured
<dependency>
<groupId>org.codehaus.jackson</groupId>
<artifactId>jackson-mapper-asl</artifactId>
<version>1.4.2</version>
</dependency>
But Spring 4.x requires jackson v2
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-core</artifactId>
<version>2.5.4</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.5.4</version>
</dependency>
Also you can read more about json serialization in Spring 4.x on Spring official blog