Request a bundle size exception for existing UI extensions
Shopify developer change
MerchantDiff detected this entry in Shopify's official developer changelog on September 17, 2026.
This Shopify update is categorized as API, Update, Admin Extensions, Checkout UI, Customer Accounts, POS Extensions.
What changed
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. 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.
Who is affected
Developers maintaining Shopify POS apps or POS UI extensions should review this change.
What action may be needed
Review the official Shopify entry, confirm whether the change touches your app, and test the affected workflow before your next relevant deployment.
Use the official Shopify entry below as the source of truth for technical implementation details, affected APIs, migration instructions and deadlines.
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