Starting with API version 2026-10, Checkout and Customer Account UI extensions can specify an for each metafield declaration in shopify.extension.toml. Starting with API version 2027-01, is required for every metafield declaration, and deployments without it will be blocked.
What changed
Metafield declarations in [[extensions.metafields]] and [[extensions.targeting.metafields]] accept a new property. names the resource that owns the metafield, such as PRODUCT or CUSTOMER.
Shopify uses to fetch only the metafields from the resource types your extension needs, which improves extension performance. On API version 2027-01 and later, every metafield declaration must include .
Who's affected
Checkout and Customer Account UI extensions that declare metafields in shopify.extension.toml and use API version 2027-01 or later are affected.
Extensions that don't declare metafields in shopify.extension.toml are unaffected.
What to do
On API version 2027-01 or later, deployments will be blocked if any metafield declaration is missing an . Add to each metafield declaration before you upgrade. You can add it now on 2026-10.
To migrate:
- Open your extension's
shopify.extension.tomlfile and add the appropriatevalue for each metafield declaration. - If your extension needs the same
namespaceandkeyfrom multiple resource types, create a separate declaration for each. - Redeploy the extension and confirm that the deployment completes without validation errors related to metafield declarations.