The most common issue I've run into during the conversion was the handler method not being hit at all. This usually results in a response code 415 from Spring (media type not accepted). Debugging this ranges from simple to aggravating. Here are a few tips, from most obvious to least:
- Is the request path correct?
- Does your request Content-Type match the "consumes" parameter of the handler
- Are all your path elements matched correctly?
- Is the HttpMessageConverter you expect to be hit -- based on the requested content type -- actually being invoked?