Why did I get a Duplicate Product/Service error message?

This happens when you have the service titles under Setup > Services in Full Slate set up with the exact same title as in your QuickBooks Online account. Since we do not pull your services from QBO, but rather from the Full Slate service list when we send the service to QuickBooks Online, it cannot match any of your existing services in QuickBooks Online. If you either change the title of the service in Full Slate or QuickBooks Online and try to checkout the appointment again, it should now work.