@soupbone38 Hi and welcome to the Forum 
The upgrade from SLE 12 SP5 to SLE 15 SP5 can only be done offline. See SLES 15 SP5 | Upgrade Guide | Upgrading offline
Ref: SLES 15 SP5 | Upgrade Guide | Upgrade paths and methods
@soupbone38 Hi and welcome to the Forum The upgrade from SLE 12 SP5 to SLE 15 SP5 can only be done offline. See SLES 15 SP5 | Upgrade Guide | Upgrading offline
Ref: SLES 15 SP5 | Upgrade Guide | Upgrade paths and methods