Entry & in table T169V is incomplete

What causes this issue?

In entry &V1& of table T169V, not all posting keys have been
maintained.

System Response

No invoices can be posted without these entries.

How to fix this error?

Please maintain the entries.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.