Fulfillment service callback url is now optional

As of the Admin API version 2026-01, the callbackUrl argument in the fulfillmentServiceCreate and fulfillmentServiceUpdate mutations is now optional.

If your app's fulfillment services do not have a callback URL but have either inventoryManagement or trackingSupport enabled, they will need to submit the information required by these features via the API.

• For submitting tracking information and handling fulfillment requests, refer to our documentation on building for Fulfillment Services.
• For managing inventory quantities, see our documentation on managing Inventory Quantities and States.

How will this change affect my app?

This is a non-breaking change. If your app currently provides a callbackUrl, it will continue to function as before. You now have the option to create or update services without a callbackUrl.

What do I need to do?

No action is required for existing apps.

For new apps, you can omit the callbackUrl argument when creating or updating fulfillment services if your operations do not depend on these callbacks.