What is the reason for this PKAddPaymentPassError.systemCancelled ?

May I know what type of situation we get this following error in production environment when we test proper PAN/card ?

func addPaymentPassViewController(_ controller: PKAddPaymentPassViewController, didFinishAdding pass: PKPaymentPass?, error: Error?) {

// Error is PKAddPaymentPassError.systemCancelled

}

What is the reason for this PKAddPaymentPassError.systemCancelled ?
 
 
Q