Product &1 cannot be both product-independent and product-specific

What causes this issue?

You have defined the procurement &V1& as product-independent by
selecting the <ZK>All products</> indicator, but have also specified
one particular product. The procurement, however, can only be selected
as either product-independent or product-specific.

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?

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.