Shopify ships a new GraphQL Admin API version every quarter. Most releases are additive. A few are not. The 2025-01 release is one of the "are not": it removed a handful of fields that thousands of apps were reading, and it quietly changed the type of one of the most common fulfillment fields from a string to an object.
The endpoint still returns 200 OK. The query still parses. The field your code reads just isn't there anymore — or it's there under a new name with a completely different shape.
If you upgraded a Shopify app from 2024-x to 2025-01 without reading the full release notes and you're seeing "this field is empty now" in production, this is probably why.
The heldBy → heldByApp Change
On a FulfillmentHold object, the 2024-x GraphQL schema returned:
