No relationships exist for document &. It is not possible to delete

What causes this issue?

Links for the document exist that cannot be executed in the Business
Document Navigator (BDN).
It is therefore not possible to delete the document in the BDN.

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?

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.