In my project there is a feign client with this method

@PostMapping(path = "/docs/{docId}")
ObjectDto createDocument(@PathVariable("docId") UUID docId, @RequestParam("userId") String userId, MultiValueMap<String, ?> doc);

This used to work before upgrading to Spring Boot 3.3.0

After the upgrade it throws a 400 Bad Request error.

I suspect the request is not even reaching the other application because no matter what I do, there is no request being logged or 400 error being thrown on the receiving end (Although other requests are being logged).

I tried changing the path to “/ds/{docId}” to see if I would get a 404 but it returns a 400 Bad Request again.

Debug and printing the error don’t provide any more information.
I’ve set feign.client.config.default.loggerLevel to FULL and logging.level.root to TRACE but no luck.

The only thing I’ve been able to figure out is that if I change the client method and the
server endpoint and remove the MultiValueMap<String, ?> doc parameter, the request works.

I’ve tried sending a @RequestPart(“file”) MultipartFile file and adding consumes = “multipart/form-data” in case the error was caused by the MultiValueMap, but I still get the same error.

@PostMapping(path = "/docs/{docId}", consumes = MULTIPART_FORM_DATA_VALUE)
ObjectDto createDocument(@PathVariable("docId") UUID docId, @RequestParam("userId") String userId, @RequestPart("file") MultipartFile file);

Any ideas what’s wrong with it or how I can get more information regarding what’s wrong with the request?