unknown_actor

The original caller of a held order can't be verified; nothing was sent.

HTTP 401. Nothing reached the broker.

Likely cause: The credential that sent it no longer exists.

What to do: Send the order again with a current credential.

Retry: No. The same request gets the same answer; change something first.

Listed under Pre-trade hooks, holds and kill switches in Errors. Send the error’s requestId to support and we can find the request.