When processing an order, you might run into the "Delivery address: Invalid address state" error.
This error relates to incorrect information in the order you're trying to process.
Feel free to follow the step-by-step guide written below or the video guide, as you prefer:
To solve this issue you will have to:
1. Find the order through any of the possible ways (after Import Orders, Batches, Order History, etc) as it applies to the case
2. Click the edit button of the order you wish to change
3. Change the address so that the Country and State combination is correct
4. Press Save to apply the changes
If the rest of the information in the order is correct, you will be able to process it.