# X_IDEMPOTENCY_RESERVATION_LOST

## Means

an idempotent action's reservation was taken over before its transaction could settle it

## Typical cause

`postgresIdempotencyStore`, settling inside the handler's transaction. The call ran past the request deadline (the app's `requestTimeoutMs`) with its record still in flight, a retry under the same `Idempotency-Key` reclaimed the key, and this attempt's settlement then matched no row. The refusal rolls this attempt's transaction back, so the write is applied by the retry and never twice

## Fix

`resend this request with the same Idempotency-Key — the attempt that took the key over answers it, and this one's transaction was rolled back`

[Actions](/error-codes#actions)