We have one custom app running on a production site, which adds discounts to line items on the checkout based on customer type. App is working fine and has "write_checkouts" scope.
However when I try to run same app on development app - development store I get this error upon PUT request to checkout:
Thanks for getting in touch - I think the best place for this will be to raise this situation with Partner Support and they'll be able to advise. Apologies if you've been directed to the wrong place initially!
You can contact Partner Support by following the guide here/direct from your Partner Dashboard - if you supply Partner Support with the app name and the store you've seen this checkout error on, they'll be able to help you out - feel free to reference this forum post in your interaction with them. Hope that helps!