What causes this issue?

No material is assigned to the equipment selected during the search for
replacement piece of equipment / replacement component. There is
neither a serial material nor a construction type material which could
be copied.

System Response

No material is copied.

How to fix this error?

Choose a piece of equipment to which either a construction type or a
serial material is assigned.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.