Items rel.to cash disc.total & larger than open item amnts total &

What causes this issue?

The discountable amount in the customer/vendor items is to be
determined by the system. All cash discount relevant G/L account or
asset items are added to this. The resulting total &SY-MSGV1& is larger
than the total of invoice amounts &SY-MSGV2&.

How to fix this error?

If the calculated amount is not correct, specify the discountable
amount specifically in the invoice items.
To avoid incorrect cash discount deductions, you can also enter the
cash discount amount directly.

Error message extract from SAP system. Copyright SAP SE.