Error 2005: Attachment owner unavailable

{
  "error": {
    "status": 500,
    "code": 2005,
    "message": "Relay could not resolve the trusted owner of an Attachment operation.",
    "doc_url": "https://docs.relayapp.im/error/codes/2xxx/2005"
  },
  "success": false,
  "trace_id": "b923d71e50be43ba9e0fe1e34a7676c2"
}