New `owner_type` field for metafield declarations in Checkout and Customer Account UI extensions, required in 2027-01

Starting with API version 2026-10, Checkout and Customer Account UI extensions can specify an owner_type for each metafield declaration in shopify.extension.toml. Starting with API version 2027-01, owner_type 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 owner_type property. owner_type names the resource that owns the metafield, such as PRODUCT or CUSTOMER.

Shopify uses owner_type 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 owner_type.

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 owner_type. Add owner_type to each metafield declaration before you upgrade. You can add it now on 2026-10.

To migrate:

1. Open your extension's shopify.extension.toml file and add the appropriate owner_type value for each metafield declaration.
2. If your extension needs the same namespace and key from multiple resource types, create a separate declaration for each owner_type.
3. Redeploy the extension and confirm that the deployment completes without validation errors related to metafield declarations.

Related docs

• Configure metafields for Checkout UI extensions
• Configure metafields for Customer Account UI extensions