Not able to create a fulfillment order for my sales order using automation.

[VishGateWay]

Hi everyone,

I’m currently working on creating a fulfillment for an order using the Shopify Admin API via a private app. I'm running into an issue when trying to create a fulfillment through the following endpoint:

POST /admin/api/2024-07/orders/{order_id}/fulfillments.json

I consistently receive a 406 Not Acceptable response, even though I’ve verified the following:

• The order is fully paid and appears as "Unfulfilled" in the Shopify Admin UI.

• I'm using a valid location_id retrieved from /admin/api/2024-07/locations.json.

• The line_item.id I'm referencing has a positive fulfillable_quantity and requires shipping.

• The request is made using a private app with the correct scopes: write_fulfillments, read_orders, etc.

• The Content-Type and X-Shopify-Access-Token headers are properly set.

When I retrieve the order via the Admin API (/admin/api/2024-07/orders/{order_id}.json), the fulfillment_status field returns null, even though the Admin UI shows “Unfulfilled”.

I’ve also tested this with other API versions like 2025-01 and 2025-04, but the issue persists.

Has anyone experienced a similar problem or found a workaround for this 406 error? I'd really appreciate any guidance or insights!