Changes to the Order API Cancel endpoint This post is outdated
On March 1st, Shopify will prevent cancellations of fulfilled or partially fulfilled orders.
Post-fulfillment order cancellations are rare and can lead to confusing fulfillment states and discrepancies in reporting. Thus, attempting to cancel a fulfilled or partially fulfilled order using the Orders API cancel endpoint will return an error.
If you have any questions, concerns, or a specific use case that will be impacted by this change, don't hesitate to reach out in the thread below!