Payments to &1 are not allowed for purchase order &2

What causes this issue?

You want to create an invoice for an invoicing party that is not allowed
as a payee.

System Response

The settings in transaction OMRM define whether the system issues this
message as a warning or an error message, or not at all. If the message
is issued as an error message, the system cannot post the invoice
document.

How to fix this error?

As standard, the system does not issue this message. You can change the
message type in Customizing for <ZK>Logistics Invoice Verification</>
(transaction OMRM).

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.