NO_PRIMARY_IDENTIFIER

This page is what Problem.type points at when the Gateway returns NO_PRIMARY_IDENTIFIER.

HTTP status	400
Retryable	No — retrying the same request produces the same result.
What to do	Supply an identifier that resolves to a subject

{
  "type": "https://dev.listrar.com/errors/NO_PRIMARY_IDENTIFIER",
  "title": "…",
  "status": 400,
  "code": "NO_PRIMARY_IDENTIFIER",
  "detail": "…",
  "request_id": "req_01K3D5NQ8XJ0R9Y2F4W6T7B8CV",
  "retryable": false
}

Dispatch on code, not on title or detail — those are for humans and their wording is not part of the contract. detail is truncated to 64 characters and never echoes raw caller input beyond that.

Quote request_id in any support request: it identifies this exact call in our audit log.

See the full error table for every code, and typed absence for why a missing product is not an error at all.