Upgrading ESXi Hosts - VMware
docs.vmware.com › en › VMware-vSphereStarting with vSphere 6.0, you can PXE boot the ESXi installer from a network interface on hosts with legacy BIOS or using UEFI. Upgrading Hosts by Using esxcli Commands By using vSphere CLI, you can upgrade a ESXi 5.5 host or ESXi 6.0 host to version 6.5 and update or patch ESXi 5.5, ESXi 6.0, and ESXi 6.5 hosts.