ITrack/Quickbooks/Object specified in the request cannot be found

Object "[some Quickbooks ID]" specified in the request cannot be found. QuickBooks error message: Invalid argument. The specified record does not exist in the list. Code: 3120.

Cause

This usually happens because something became unsynced between ITrack and Quickbooks (some object was altered in Quickbooks in such a way that Quickbooks gave it a new ID that ITrack doesn't know about).

Solution

In the case of a Invoice or Payment, you probably need to go to customer tab on the Quickbooks screen and double click the customer on the invoice/payment, then select the correct corresponding customer in Quickbooks. Then try to repush the invoice/payment to Quickbooks.