QBO Error: Invalid account type used: Invalid account type: For a stock product, the expense account must have Account Type: 'Cost of Sales' and Detail Type: ‘Supplies.'

Product Type in QuickBooks Online is set to "Inventory" instead of "Service". To fix the issue, you will need to change it to Service in your QuickBooks account. If you are unsure of how to change the product type in QuickBooks, please reach out to QuickBooks support for further assistance.