In Shopify, the default behavior is to limit product sales when you don't have sufficient quantity in stock. Your customers will see a message indicating they can reduce the ordered quantity to the amount you have in stock, or remove the item from the order. This helps prevent orders from being created when there is insufficient quantity in stock. You can manage this behavior in the Item Variant window. If you set the Allow users to purchase this item, even if it is no longer in stock flag, you can sell items even if there is no quantity in stock.

In AccountEdge, you cannot sell a product unless you have sufficient stock on hand to fulfill the invoice. In AccountEdge, you can also control this feature by setting Allow the Sale of Items with Insufficient On-Hand Quantities [System-Wide] in the Setup > Preferences > Inventory window. Alternatively, you can create a customer Order, which you can fulfill when you do get enough quantity to satisfy the order.

If you do not allow the sale of items when there is insufficient quantity in Shopify, and disallow the sale of items with insufficient quantity in AccountEdge, erroneous orders will not be created. On the other hand, if stock quantities between the 2 systems are incorrect, it could be possible for your customer to order an item when a quantity does not exist.

All orders from Shopify will be brought into AccountEdge as Invoices as long as there are sufficient on-hand quantities. If the Allow the Sale of Items with Insufficient On-Hand Quantities [System-Wide] preference has been enabled in the AccountEdge company file, the Order will be brought in as an invoice, and the Shopify Log will be noted as such. If there is an insufficient on-hand quantity and the Allow the Sale of Items with Insufficient On-Hand Quantities [System-Wide] preference is not selected, the Shopify order will be brought in as an Order that can be fulfilled when a sufficient quantity is available in AccountEdge. The item quantity must be transferred to, and fulfilled through Shopify, however.

Use the Item Information > Locations window to set Track Inventory for an item in Shopify, and define the Target quantity of your available quantity to be used to satisfy Shopify orders. As long as there are sufficient quantities available, your target quantity will be synced to Shopify.