I Can't update a fulfilment on an existing order.

Shopify Apps

Topic summary

A developer is encountering a 406 Not Acceptable error when attempting to update an existing fulfillment via Shopify’s Admin API (version 2024-10).

Current Setup:

  • Using a private app with all necessary permissions enabled
  • Successfully performing other operations: reading/updating products, retrieving orders, and getting fulfillment IDs
  • Has correct order ID (5924257104212) and fulfillment ID (5329461772628)
  • Attempting to update tracking information (tracking number, tracking URL, carrier company) with notify_customer: true

Key Issues:

  • Cannot update the existing fulfillment despite proper authentication and IDs
  • Cannot create a new fulfillment (likely because order already has one)
  • Working with an older order, questioning if archival status might be causing problems

Status: The issue remains unresolved with no responses yet. The developer is seeking guidance on what might be causing the 406 error.

Summarized with AI on November 4. AI used: claude-sonnet-4-5-20250929.
1

Hi I have a private app and have enabled all the requirements needed.

I can update/read products, get order, get fulfilment ID

I have the correct fulfilment & order IDs

When I try to update a fulfilment ID I get a 406Not Acceptable error

curl --location --request PUT ‘https://myShop.myshopify.com/admin/api/2024-10/orders/5924257104212/fulfillments/5329461772628.json’
–header ‘Content-Type: application/json’
–header ‘X-Shopify-Access-Token: myToken’
–data ‘{
“fulfillment”: {
“tracking_number”: “new_tracking_number_123”,
“tracking_urls”: [“https://trackingurl.com/track/new_tracking_number_123”],
“tracking_company”: “New Carrier Name”,
“notify_customer”: true
}
}’

I am updating an old order ( so not to cause any issues ) Could it be archived ?

Also I cannot create a fulfilment ( I presume because the order already has a fulfilment done)
Any ideas please.