API errors

bad_request

The request was malformed or a parameter had a value the endpoint cannot act on.

400application/problem+json

What it means

The API could not accept the request as sent: the body could not be parsed, or a value is not one the endpoint can act on. The single problem is described in detail.

Field-level validation failures have their own code, validation_failed, which carries a per-field errors array. A bad_request body has no errors array.

400 · application/problem+json

{
  "type": "https://developers.firsty.app/errors/bad_request",
  "title": "Bad request",
  "status": 400,
  "detail": "Malformed JSON in request body",
  "code": "bad_request"
}

How to handle it

Read detail. It names the missing parameter or the invalid value.
Fix how the request is built and resend. The same request fails the same way every time, so do not retry it unchanged.

Errors reference