400
payments.invalid_outcomepaymentsUnknown outcome value
Returned by the implementation; no specification rule declares it yet.
An internal transition was asked for an outcome that is not in the enum. On the partner surface this means a refund decision or provider outcome was sent with a value outside the documented set.
Why the API refuses
unknown provider outcome
What to do
Use the enum from the reference page for the operation you are calling. If you did not send an outcome at all and still see this, report it with the X-Request-Id — that is a bug on our side, not yours.