Security class cannot be deleted because group cannot be deleted

What causes this issue?

The security class cannot be archived because the security group cannot
be archived. This is due to one of the following reasons:
The security class group contains a non-archivable security class.
The security class group is incomplete.
The end of the residence period for the security group is not reached.

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.