404
checkout.no_qrcheckoutThis checkout has no QR to show
Returned by the implementation; no specification rule declares it yet.
The payment's current next_action is not a QR — either the method does not use one, or the attempt has not produced it yet, or the payment has moved on.
Why the API refuses
this checkout has no QR to show
What to do
Read next_action and render what it says rather than assuming a QR. A payment that has just been created has no attempt yet: start one, then show whatever the attempt's next_action carries.