Failed on updating invoice with Credit Memo. This error happens when an invoice in QBO collects payment from a credit memo, but that credit memo has already been applied to an invoice in ConnectWise. ConnectWise is then reporting back that the balance of the credit memo that isn't great enough to match the amount being applied to the invoice in QBO.
You will then see the following error message.
"The amount of $$$ was attempted to be applied from Credit Memo ### toward invoice ### in Quickbooks Online; however, this Credit Memo only has a usable balance of $$$ in ConnectWise manage"
Typically, this happens when a Credit Memo's balance is partially used toward an invoice in ConnectWise. Simultaneously, the same credit memo is used to create a payment in QBO toward another invoice with an amount that is greater than the remaining balance of the same Credit Memo in ConnectWise.
Ideally, to fix this error we would recommend that you first determine what is actually being spent where, since this error is here to inform you that a credit memo is being over-spent somewhere. Then we would recommend removing both payments (QBO AND ConnectWise), and then sorting out where you are actually meaning to apply the credit memo so that the expenditure is sufficiently under the total balance. Once you have fixed where the credit memo is to be applied you can then re-run your payment sync to clear this error.