415 Unsupported media type

The request carried a body that is not JSON. Every request body this API accepts is JSON; a JSON body is read whatever Content-Type it was sent with.

Retry only after changing the request

What causes it

• The Content-Type header was missing, so the client sent its default (curl -d sends application/x-www-form-urlencoded, a bare fetch with a string body sends text/plain).
• The body was sent as a form or as plain text.

How to fix it

• Send the body as JSON with the header "Content-Type: application/json" (a charset parameter is fine).
• Endpoints that take no body (approve, send, convert and the like) need no Content-Type: send no body at all.

Example response

HTTP/1.1 415
Content-Type: application/problem+json

{
  "type": "https://sealdeal.ai/errors/unsupported-media-type",
  "title": "Unsupported media type",
  "status": 415,
  "detail": "..."
}

`type` is stable and safe to branch on in code. `detail` is specific to your request and is the field to read for the particulars; its wording may change.