you'll get a valid migration key in SAPnet: "Note that the generation of migration keys is a self service and can be requested with the relevant authorizations on SAP Service Marketplace under http://service.sap.com/migrationkey."
or use SAPnote 1768158 (for SAP NW 700 based systems) or SAPNote 1738258 (for SAP NW 710 and higher based systems) as a workaround 
GreetZ, AH