The used object, &1 &2, is not visible

What causes this issue?

The development object used, &V1& &V2&, is not contained in any package
interface. However, the "Package Check as Client" indicator is set for
the related client package &V3&.

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?

To resolve the message, first assign the development object used to one
or more package interfaces according to the package concept. Then create
a use access for the client package, again according to the package
concept.
You can simply ignore this message, since it is an information message,
not an error.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.