It can be frustrating when you see an error while trying to post an invoice to Quick Books. The most common reason why you would not be able to post an invoice to Quick Books would be that the information in Quick Books does not match the information on the invoice.
If the customer name, or the item has changed somehow in Quick Books, and if you synced over those changes to The Service Program, then the invoice most likely needs to be refreshed with the updated data. Simply re-select the customer name, and all of the items on the invoice, and then try again :
Another reason why an invoice will not post to Quick Books is if you have the delivery method of the invoice set to email, but the customer does not have an email address in Quick Books:
Finally, the last most common reason why an invoice will not post to Quick Books would be if the invoice has an old or not matching sales rep, or class record. Simply click on Update Quick Books, and reload class and or sales reps: