To upgrade ESXi 5.5 hosts or ESXi 6.0 hosts to ESXi 6.5, you can boot the ESXi installer from a CD, DVD, or USB flash drive.
Before upgrading, consider disconnecting the network storage. This action decreases the time it takes the installer to search for available disk drives. When you disconnect network storage, any files on the disconnected disks are unavailable at installation. Do not disconnect a LUN that contains an existing ESXi installation.
Prerequisites
- Verify that the ESXi installer ISO in one of the following locations.
- On CD or DVD. If you do not have the installation CD or DVD, you can create one. See Download and Burn the ESXi Installer ISO Image to a CD or DVD
- On a USB flash drive. See Format a USB Flash Drive to Boot the ESXi Installation or Upgrade
Note: You can also use PXE to boot the ESXi installer to run an interactive installation or a scripted installation. See PXE Booting the ESXi Installer. - Verify that the server hardware clock is set to UTC. This setting is in the system BIOS.
- ESXi Embedded must not be on the host. ESXi Installable and ESXi Embedded cannot exist on the same host.
- If you are upgrading an ESXi host, supported custom VIBs that are not included in the ESXi installer ISO are migrated. See Upgrading Hosts That Have Third-Party Custom VIBs
- See your hardware vendor documentation for information about changing the boot order.