Keep getting this error when pushing orders to QuickBooks Online?
Error 620: TxnID cannot be linked
An invoice / sales receipt record with this number already exists in QuickBooks. Additionally, this invoice / sales receipt in QuickBooks exists under a different customer than the customer for the order in WooCommerce is mapped to in QuickBooks. This almost always means that the existing invoice / sales receipt record in QuickBooks is a totally different/unrelated record.
This most likely means that there is already an invoice/sales receipt in QuickBooks with the same number as the WooCommerce order - and it is a completely different record. This usually happens when QuickBooks has been used for a long time, and a new order in a new WooCommerce store has the same number as an invoice/sales receipt from earlier on in the company.
In order to resolve this, review the steps in our documentation article that addresses how to handle WooCommerce orders that already exist as different orders in QuickBooks.