---
title: >-
  Request a bundle size exception for existing UI extensions - 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/request-a-bundle-size-exception-for-existing-ui-extensions
  md: >-
    https://shopify.dev/changelog/request-a-bundle-size-exception-for-existing-ui-extensions.md
metadata:
  effectiveApiVersion: ''
  affectedApi:
    - displayName: Admin Extensions
      handle: admin-extensions
    - displayName: Checkout UI
      handle: checkout-ui-api
    - displayName: Customer Accounts
      handle: customer-accounts
    - displayName: POS Extensions
      handle: pos-extensions
  primaryTag:
    displayName: API
    handle: api
  secondaryTag:
    displayName: Update
    handle: update
  indicatesActionRequired: false
  createdAt: '2026-09-17T14:55:02-04:00'
  postedAt: '2026-09-17T15:30:00-04:00'
  updatedAt: '2026-09-17T15:25:02-04:00'
  effectiveAt: '2026-09-18T15:15:00-04:00'
---

September 17, 2026

# Request a bundle size exception for existing UI extensions

DateSeptember 17, 2026

FlagsUpdate

SurfacesAPI

Affected APIs[Admin Extensions](https://shopify.dev/changelog?api_type=admin-extensions)[Checkout UI](https://shopify.dev/changelog?api_type=checkout-ui-api)[Customer Accounts](https://shopify.dev/changelog?api_type=customer-accounts)[POS Extensions](https://shopify.dev/changelog?api_type=pos-extensions)

UI extensions using API version `2025-10` or later are limited to a 64 KB compressed JavaScript bundle per extension. Full page customer account extensions may use up to 128 KB. If your extension remains over the limit after optimization, run `shopify app build` and submit the minified bundle and its esbuild metafile through the bundle size exception [form](https://docs.google.com/forms/d/e/1FAIpQLSeb3yjIfdAardxHZo9DrZW_Qzx88javl_4Zm8Q29N6xCk_rMw/viewform).

Shopify will review the contents of your bundle and may grant a limit increase if the remaining bundle weight is unavoidable.

Requests will be denied for avoidable bundle weight, including heavy libraries, duplicate dependencies, and translations bundled with the extension instead of provided through the native localization APIs.

To remain deployable after October 1, 2026, an app must ensure that every existing UI extension uses API version 2026-01 or later.

**Learn more**

* [Optimize bundle size for UI extensions](https://shopify.dev/docs/apps/build/app-extensions/optimize-bundle-size)