HttpMediaTypeNotAcceptableException: Could not find acceptable representation in exceptionhandler

Question

I have the following image download method in my controller (Spring 4.1):

@RequestMapping(value = \"/get/image/{id}/{fileName}\", method=RequestMethod.GET)
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Answer 1

Pay attention to your HTTP Accept header. For example, if your controller produces "application/octet-stream" (in response), your Accept header should NOT be "application/json" (in request):

@GetMapping(value = "/download", produces = MediaType.APPLICATION_OCTET_STREAM_VALUE)
public void download(HttpServletResponse response) {}

Answer 2

You need to decide how the media type of the response should be determined by Spring. That can be done in several ways:

• path extension (eg. /image.jpg)
• URL parameter (eg. ?format=jpg)
• HTTP Accept header (eg. Accept: image/jpg)

By default, Spring looks at the extension rather than the Accept header. This behaviour can be changed if you implement a @Configuration class that extends WebMvcConfigurerAdapter (or since Spring 5.0 simply implement WebMvcConfigurer. There you can override configureContentNegotiation(ContentNegotiationConfigurer configurer) and configure the ContentNegotiationConfigurer to your needs, eg. by calling

ContentNegotiationConfigurer#favorParameter
ContentNegotiationConfigurer#favorPathExtension

If you set both to false, then Spring will look at the Accept header. Since your client can say Accept: image/*,application/json and handle both, Spring should be able to return either the image or the error JSON.

See this Spring tutorial on content negotiation for more information and examples.