We’ve implemented shipping rate calculations using the CarrierServiceCreate mutation with a callback URL. Our system relies on third-party logistics providers to return shipping rates through cart-checkout webhooks, as order-specific information is required to determine accurate rates.
Identified Issue:
-
The Carrier Service callback triggers before cart checkout completes
-
This creates a dependency conflict since order details (required for rate calculation) only become available during checkout
-
External provider responses sometimes exceed Shopify’s timeout window
-
Result: “Shipping cannot be processed for the specified address” error during checkout
Key Challenge:
The callback system appears to require order information that only becomes available post-checkout initiation, creating a circular dependency where:
Carrier Callback (needs rates) → Checkout (needs rates) → Order Data
Request:
Could you advise on either:
-
A recommended pattern to access preliminary order data earlier in the flow, or
-
Alternative implementation approaches that align callback timing with checkout completion?
We’d appreciate guidance on resolving this timing mismatch between carrier service callbacks and checkout webhook availability.