No documents for period-end billing period found for contract &1

What causes this issue?

The system attempted to read the billing documents of the final billing
period starting on &v2& for contract &v1&. No billing documents were
found.

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?

Error message extract from SAP system. Copyright SAP SE.