SAP Message UCF8021 - Reference document &1 is both a reversal document and a reversed document

Diagnosis
Reference document &V1& is itself reversed by documentnumber/period/fiscal year &V2&, but it also reverses documentnumber/period/fiscal year &V3&.

System Response
This document cannot be reversed.

Procedure
Select a document that is not yet reversed, or does not reverse anotherdocument.