[Spryng] Why does the «refundTransaction» API method respond «invalid requested resource»?

I call the refundTransaction API method through the Spryng PHP SDK using the \SpryngPaymentsApiPhp\Controller\TransactionController::refund() method:


It makes a POST HTTP request to: https://sandbox.spryngpayments.com/v1/transaction/58a96bd2b7f62b516188beef/refund

The Spryng API server responds:

	"code": 110,
	"details": {
		"resource": "transaction",
		"invalid_fields": [
	"message": "invalid requested resource"

I have got an answer from Spryng:

You can only refund transactions with the status SETTLEMENT_COMPLETED