Special turnover exists for supplier &

What causes this issue?

Financial accounting has made down-payments to the supplier whose
invoice you are currently processing.

How to fix this error?

If you want to explicitly allocate a down payment to an invoice, you
must make a manual transfer posting. To do this, choose the function
<LS>Invoice verification</> --> <LS>Environment</> --> <LS>Clear down
payments</>.

Error message extract from SAP system. Copyright SAP SE.