Cause

externalReference is already used by another resource for this rental operator account.

Partner action

Use a unique externalReference per account, or omit it. Query existing resources before retrying.

Gando action (internal)

Check unique constraint on (account_id, external_reference) for the resource type.

Example response

{
  "error": {
    "code": "external_reference_conflict",
    "message": "externalReference already exists for this account",
    "requestId": "req_abc123"
  }
}