If you are PXE-booting the installer, verify that your network PXE infrastructure is properly set up. See Media Options for Booting the ESXi Installer. Determine where you want to locate and boot the ESXi installer.Prepare your environment before upgrading.Verify that your system meets the upgrade requirements.Overview of the ESXi Host Upgrade Process See Upgrading Hosts That Have Third-Party Custom VIBs. When you upgrade an ESXi 5.5.x host or 6.0.x host that has custom VIBs to version 6.5, the custom VIBs are migrated. You can upgrade a ESXi 5.5.x host or 6.0.x host, asynchronously released driver or other third-party customizations, interactive upgrade from CD or DVD, scripted upgrade, or upgrade with vSphere Update Manager. See VMware Product Interoperability Matrixes at. Verify support for the upgrade path from your current version of ESXi to the version to which you are upgrading. The details and level of support for an upgrade to ESXi 6.5 depend on the host to be upgraded and the upgrade method that you use. VMware provides several ways to upgrade ESXi version 5.5.x and version 6.0.x hosts to ESXi 6.5.
