UI extensions now support a larger number of locales
Shopify developer change
MerchantDiff detected this entry in Shopify's official developer changelog on October 30, 2026.
This Shopify update is categorized as Platform, Update.
What changed
Previously, the total size of the locale files in a UI extension's locales folder couldn't exceed 256 KB. Extensions with many languages could reach that limit and fail to deploy, which forced you to trim translations or drop languages. That combined limit is now removed. The 30 KB limit for each individual locale file still applies. Locale files keep the same format, file naming, and fallback behavior described in the checkout UI extension localization guide.
Who is affected
This change applies to every app that includes UI extensions with locale files, on all API versions. Existing extension versions keep working as before. New deploys aren't limited by the combined size of locale files.
What action may be needed
You don't need to take any action. If you previously removed languages or shortened translations to stay under 256 KB, you can add them back: Add the locale files you need to your extension's locales folder, for example de.json or pt-BR.json. Keep each file under 30 KB. Run shopify app deploy to release a new app version.
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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