/rs/soap/shipment (…) element customs-value-per-unit value ‘0’ is not valid [Solution]

When processing orders you might come across the "/rs/soap/shipment (…) element customs-value-per-unit value ‘0’ is not valid" error.

This error is shown when the value entered for the SKU (within the Packaging) is missing or invalid invalid.

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. Select the Packaging tab

4. Make the necessary changes in the order, entering a valid Unit Price for each SKU without it

5. Press Save to apply the changes

If the rest of the order's information is correct, you will be able to process it.