Partner & not authorized for selected transaction type

What causes this issue?

Authorization information is defined in the business partner (bank area
independent data). According to this information, the business partner
does not have authorization for the selected transaction type.

System Response

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

How to fix this error?

Maintain the transaction authorizations standing instructions for the
relevant partner and a combination of contract type, product type and
transaction type.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.