When I was developing the fulfillment service, I followed this document to develop https://shopify.dev/docs/apps/fulfillment/fulfillment-service-apps/manage-fulfillments
But I found a problem when I was in the eighth and ninth steps, I did not receive the request from <callback_url>/fetch_stock, but I received
Request for <callback_url>/fulfillment_order_notification
Has anyone had a similar problem like me?
Topic summary
Issue: A developer implementing a Shopify fulfillment service (per the Manage Fulfillments guide) did not receive requests to <callback_url>/fetch_stock during steps 8–9, but did receive <callback_url>/fulfillment_order_notification.
Clarification: A fulfillment service can receive both endpoints. /fetch_stock is used by Shopify to retrieve inventory for an individual SKU; /fulfillment_order_notification informs the service about fulfillment order events.
Conditions for /fetch_stock: It is only called when fulfillment_service.inventory_management is set to true and a qualifying trigger occurs, such as:
- Initial product setup
- SKU change in Shopify admin
- Switching a product’s inventory management to use the fulfillment service
Action items:
- Verify fulfillment_service.inventory_management is true.
- Ensure a /fetch_stock trigger actually occurred (e.g., change SKU or set inventory management to the service).
Status: No confirmed resolution yet; awaiting validation of settings and triggers by the implementer.
Hi there 
Your fulfillment service can expect to receive requests for both <callback_url>/fetch_stock and <callback_url>/fulfillment_order_notification.
If fulfillment_service.inventory_management is set to true, then Shopify makes a request to the /fetch_stock endpoint for the inventory of an individual SKU when the product is set up initially, when its SKU is changed in the Shopify admin, or when its inventory management is set to use the fulfillment service. I would recommend verify that fulfillment_service.inventory_management is set to true and a /fetch_stock trigger occurred.