Message is not in a replayable state

https://tandem.codingful.com/problems/message-not-replayable

What it means

Replay was requested for a message that is not in a replayable state. Only DONE and FAILED messages can be replayed.

A PENDING or IN_FLIGHT message is already on its way to the broker: replaying it would queue a second delivery of an event the relay is about to publish anyway, and — worse — would reorder it against the rest of its aggregate.

What to do

Nothing, usually. Re-read the message: if it is IN_FLIGHT the relay is working on it, and if it fails it will land in FAILED, where replay applies. Retrying the replay call immediately is not useful — this is a state conflict, not a transient error.

Example

{
  "type": "https://tandem.codingful.com/problems/message-not-replayable",
  "title": "Message is not in a replayable state",
  "status": 409,
  "detail": "Message 4711 is IN_FLIGHT; only DONE or FAILED can be replayed"
}