Bundle size and API version are separate deployment checks. An extension team should resolve both before scheduling its next release.
Shopify published Request a bundle size exception for existing UI extensions on 17 September 2026.
Optimise first, then document unavoidable weight
For UI extensions using API 2025-10 or later, Shopify’s compressed JavaScript limits are 64 KB per extension and 128 KB for full-page customer-account extensions. An over-limit extension can request an exception after optimisation by submitting its minified build and esbuild metafile. Approval is discretionary; avoidable dependency or translation weight is not grounds for an increase.
Separately, every existing UI extension must use API 2026-01 or later for the app to remain deployable after October 1, 2026. A bundle-size exception should not be treated as an API-version exemption.
Prepare one release inventory for all extensions
Vivek Codes’ implementation advice:
- Record each extension’s target, API version, compressed build size and responsible owner. Investigate the largest imported modules before changing application behaviour, and retain the measurement alongside the release that produced it.
- If an exception is still necessary, explain the role of the remaining dependencies and the smaller alternatives considered. Schedule compatibility testing early enough that the team can address a rejected request without relying on a last-minute approval.
Read the official announcement for the release requirements. For help with this work, explore Shopify extension implementation or send Vivek Codes the implementation context.
Editorial brief based on Shopify’s announcement. The implementation advice is general guidance, not a test result for your store or app.
