When a cancellation syncs from Amazon to Shopify, Shopify needs a reason for its own records. Set a default cancellation reason so the app applies it automatically every time — no manual entry needed.

Steps

1. Go to Settings → Order Settings → Cancelation and Refund.
2. Find Default reason for cancellation and toggle it on.
3. Pick one of the available reasons from the dropdown:
   • Customer
   • Declined
   • Fraud
   • Inventory
   • Other
   • Staff
4. Save.