2.4 Upload Response
The HTTP response to the upload request will contain data returned by the server, as part of the response headers collection.
The success (or not) of the response request will be indicated by the returned “X-FTH-Error” header.
If this header field is empty, that signals that the upload request has been completed successfully; otherwise, the request failed.
Note: Because of that, the client application cannot simply rely on the HTTP response status code to evaluate the success completion of the request. A response with a status code of 200 (which, according to the HTTP standards, indicates the request succeeded) may still come from an unsuccessful request.