We are developing a custom checkout UI for our store. The store is hosted as a web app separately from Shopify and integrates it through Storefront API.
We use a private app for the purpose of connecting to Storefront API. The problem is that while completing a checkout according to this doc https://shopify.dev/tutorials/create-a-checkout-with-storefront-api#stripe we get a vague error in the admin site.
* The Stripe's token we send is correct
* Calling checkoutCompleteWithTokenizedPaymentV3 mutation returns no errors
* The private app (it's not a public app, not a sales channel) has the required permissions which are unauthenticated_write_checkouts and unauthenticated_read_checkouts.
The error we are getting in the admin site