When processing orders you might come across the "Hard 128102 - Invalid or missing sold to country code" error.
This error is shown when the Country Code used in the order does not have a correct format.
Feel free to follow the step-by-step guide written below or the video guide, as you prefer:
To do so:
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 Country Code accordingly
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.