We are currently actively trying to get additional logs in our dev environment, but it appears this call is failing for all of our merchants on the latest Shopify POS 10.19.0.
Update: I believe we have a root cause, our app creates a temporary product or variant programmatically via the Shopify API and then we immediately add this variantId to the cart. This is the way our app has worked since 2020 and this has never been an issue. It appears as of Shopify POS 10.19.0, we are now getting a “failed to fetch variant with ID: XXXXXXX” error message when we do this. It appears Shopify POS can’t find the newly-created product.
The api.cart.addLineItem call still works with older product variants created by our app, but now Shopify POS apparently can’t fetch newly-created variants.
If we add a 60s sleep in between the product creation and addLineItem call then it seems to work, but obviously we can’t ask merchants to wait over a minute for each call.
We urgently need this rolled back and resolved.