QuickBooks Online sync error: The customer on one of invoices paid in this transaction does not match the customer on that invoice in QBO. This could happen because of an incorrect customer merge in QBO

Why the sync error occurs

This error occurs when a customer is different between the payment and the invoice in QuickBooks Online. This difference may be due to:

There are three options to resolve this issue:

If the original customer is active in QuickBooks Online, update the invoice to the original customer
Select to not sync the payment and manually mark the invoice as paid in QuickBooks Online
If there was a merge and the payment should be synced, contact Customer Service to merge the customers in Bill.com