Objects exist in package &1

What causes this issue?

You want to change the transport layer of the package &V1&. However,
there are Repository objects in the package. Changing the transport
layer changes the way the objects are transported. This means that
objects may be transported through the system landscape along other
transport routes. Objects in an SAP System that is no longer provided
with transports may retain an obsolete status.

System Response

This is a warning.

How to fix this error?

Choose <PF>Enter</> to continue editing.

Error message extract from SAP system. Copyright SAP SE.