---
title: >-
  Checkout UI extensions now default to non-blocking behavior - Shopify
  developer changelog
description: >-
  Shopify’s developer changelog documents all changes to Shopify’s platform.
  Find the latest news and learn about new platform opportunities.
source_url:
  html: >-
    https://shopify.dev/changelog/posts/checkout-ui-extensions-now-default-to-non-blocking-behavior
  md: >-
    https://shopify.dev/changelog/posts/checkout-ui-extensions-now-default-to-non-blocking-behavior.md
metadata:
  effectiveApiVersion: ''
  affectedApi:
    - displayName: Checkout UI
      handle: checkout-ui-api
  primaryTag:
    displayName: Platform
    handle: platform
  secondaryTag:
    displayName: Update
    handle: update
  indicatesActionRequired: false
  createdAt: '2026-01-20T16:34:44-05:00'
  postedAt: '2026-01-26T11:30:00-05:00'
  updatedAt: '2026-01-26T08:41:58-05:00'
  effectiveAt: '2026-01-22T10:00:00-05:00'
---

January 26, 2026

# Checkout UI extensions now default to non-blocking behavior

DateJanuary 26, 2026

FlagsUpdate

SurfacesPlatform

Affected APIs[Checkout UI](https://shopify.dev/changelog?api_type=checkout-ui-api)

As of January 26, 2026, Checkout UI extensions that support blocking now default to non-blocking behavior. To enable blocking, merchants must explicitly activate the **Allow app to block checkout** setting in the checkout and accounts editor.

If your Checkout UI extension requires blocking, display a warning in the editor using the [`useExtensionEditor()`](https://shopify.dev/docs/api/checkout-ui-extensions/latest/apis/buyer-journey) hook, and include this step in your activation process. Inform merchants that they must enable **Allow app to block checkout** for the UI extension to function as intended.

We now recommend building custom checkout validation using Cart and Checkout Validation Functions instead of Checkout UI extensions, as they are more secure, performant, and guaranteed to run across supported checkouts. Learn more about [Cart and Checkout Validation Functions](https://shopify.dev/docs/apps/build/checkout/cart-checkout-validation).