QuickBooks Sync - Error 3140

There was an invalid reference to QuickBooks Account "Account"... The record does not exist in the list. (3140)

This error is the most common error when syncing to Quickbooks.  It simply means that the account in question does not exist in QuickBooks.

It is either caused by:

1. A new Charge Type added, an unlinked Charge Type or an invalid Class Name (see My Lists > Charge Types).
2. An unlinked Bank Account. Check that every bank account is linked to an account in QB by heading to admin menu > My Lists > Bank Accounts.
3. Sometimes the wrong information is entered in the financial options (see Export > Export to QuickBooks Now > Batch Customer Name). This field should only be populated with a QuickBooks Customer Name if you want to tie all Batches to that Customer. Clear it to go back to the default functionality.

Following one of these corrections, attempt the sync again to see if the error goes away.