LEGACY - Failed to sync DocNumber=XXXXXX. Business Validation Error: You must select an account for this transaction.

When syncing your Legacy QuickBooks Online integration in Finale Inventory with your QuickBooks Online account you get this message on a Purchase order line in the pre-sync list window:

This happens when you add a new product to your QuickBooks Online and you did not enable it to be purchased!

Here are the steps to resolve this:

Step 2: Add a service or product’s purchasing info

If you want to track how much you spend on a product or service:

1. Go to Get paid & pay or Sales, then select Products and services (Take me there).
2. Find the product or service on the list and select Edit in the Action column.
3. Select I purchase this product/service from a vendor.
4. Add a description. This shows on bills, purchase orders, and other forms you send to vendors.
5. Add the Cost. If the price changes, don’t worry. You can still enter the updated price when it’s time to buy supplies.
6. Select the Expense account ▼ dropdown and then the account you use to track the cost of things you sell.
7. Select your preferred vendor.
8. When you're done, select Save and close.

All of this is covered hereOn QuickBooks help center