Please enter customer OR vendor

What causes this issue?

You can only enter either the customer or the vendor as a parameter.

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?

If this message appears when you call the report, enter either the
customer or the vendor number in the selection screen.
If the message appears online, it is due to an internal error.

Error message extract from SAP system. Copyright SAP SE.