Help | Checkout Extension | To Block Postcode

Shopify Apps

Topic summary

Developer seeks help creating a Shopify Checkout UI extension to block a specific postcode (2022) during checkout. Goal is to prevent checkout when that postcode is entered.

They are using @shopify/ui-extensions-react/checkout with reactExtension, useBuyerJourneyIntercept (to intercept/guard the buyer flow), and useShippingAddress (to read the shipping address). The extension point targeted is “purchase.checkout.shipping-option-list.render-after”.

Provided code snippet is intended to block postcode 2022 but currently does not work. The snippet appears incomplete/truncated and includes only imports and a partially defined reactExtension call, so the core logic is not visible. A Banner and BlockStack are also imported, suggesting a plan to show a UI message.

No answers or guidance have been provided yet. No decisions or fixes reported. The request remains open, with the key need being working example or guidance on intercepting and blocking a postcode via Checkout UI extensions. The code snippet is central to understanding the issue.

Summarized with AI on December 12. AI used: gpt-5.
1

Hi Developer,

I am trying to create a checkout extension function that would block the postcode in the checkout page.

Below is my extension code to block postcode 2022, however, it is not working/blocking.

I would really appreciate your help and information:

import {
  reactExtension,
  useBuyerJourneyIntercept,
  useShippingAddress,
  Banner,
  BlockStack,
} from "@shopify/ui-extensions-react/checkout";

export default reactExtension(
  "purchase.checkout.shipping-option-list.render-after",
  () => 

Many thanks