Shopify requires theline_item.price field when making an import. If you try to import an order without a price, Shopify will send back an error. The price must also be numeric; if you provide a non-numeric value for the price, you will get an error during import.

For most users, you are providing and mapping the line_items. The price field to a column in your CSV file that contains the price isn't a problem. However, there are situations where the price may not be available. For these situations, you can let Shopify map the price of your line item to the price of your products. To do this, click the Link product by SKU checkbox in the Custom Configuration section and leave the line_items.price field unchecked.

When you have the Link product by SKU option checked, the line_items. The price field becomes optional. This way, Shopify knows to use the price of your product as the line_items.price. To learn more about linking your products by SKU, click here. Don't forget to map the SKU field when linking your products by their SKU. This is also true if you are using the Link product by Barcode option. 

There are two things to remember before using this feature.

1. SKUs are case-sensitive. This means the SKU in your CSV file must match the SKU on your product exactly. If the case is incorrect, the product will not be found, and the title will not be mapped.
2. The order will not be imported if the SKU can not be found. The product information will return empty, meaning the price field will be blank. Shopify will respond with a "price cannot be blank" error.