Objects from incompatible transport layers

What causes this issue?

The objects that you want to edit are assigned to transport layers that
have different transport targets (from this system).

System Response

The function terminates.

How to fix this error?

Make sure that the transport layers of all the objects you have
selected have the same transport target, and then try again.
To check the transport target of an object, first display its object
directory entry. Double-click its package to display the transport
layer.

Error message extract from SAP system. Copyright SAP SE.