Are you seeing this error either when placing a test order, or when your customers are attempting to place an order through your Shopify store?
If so, it's likely due to your Shopify shipping rates not being set up correctly.
This error appears when attempting to place an order that's either shipping to a destination not covered by the store's shipping rates, or when the items in the order are not covered by the store's shipping rates.
Inkthreadable uses weight based shipping, and so to set up your store to accurately assign the correct shipping costs in relation to what you'll pay Inkthreadable for shipping each order you'll need to use weight based shipping in your own store.
This means you could be seeing this error for one of two reasons:
The particular shipping destination is not covered by your shipping rates, or;
The weight of the order is not covered by your shipping rates.
The best way to fix this is to follow our guide on setting up your shipping rates to match Inkthreadable's.
By following this guide you will create shipping rates in your Shopify store that cover all possible order weights, and that cover all possible shipping destinations.
Please note: you don't have to follow our guide to the letter. As long as you use weight based shipping you're free to set up your rates as you'd like, charing as much or as little as you like, and shipping only to the desinations you want to ship to. Just make sure you cover the weight range from 0 kg to 30kg.