Bill. doc. &1 end of bill. period &2 cannot be reversed due to archiving

What causes this issue?

Billing document &v1& has end of billing period &v2&.
The shortest retention period in days results in the key date &v3&.
This retention period is calculated from the retention periods for the
archiving document ISU_BILL (IS-U archiving: billing document) for
manual/normal billings, final billings,and backbilling/period-end
billings, using system date &v4&.
However, the end of the billing period is before this key date. In this
case, the billing document can no longer be reversed since it is ready
to be archived.

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 you still want to reverse the billing document, create a manual
credit memo or backbilling.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.