Supplier error: only a higher amount invoiced is allowed

What causes this issue?

The item amount in the invoice of &V1& is smaller than the item amount
of &V2& suggested by the system.

System Response

You currently cannot enter an amount that is smaller than that expected
by the system. This would lead to a credit memo for the supplier.

How to fix this error?

You can change the default values to correspond to the invoice and then
post the invoice.

Error message extract from SAP system. Copyright SAP SE.