Plan all the involved steps accordingly, evaluating the impact of new features and the improvements that can be applied to the current environment. An upgrade order of the virtual components should be established to avoid potential problems. For example, the vSphere platform requires first upgrading the vCenter Server and then the ESXi hosts to avoid communication issues within vSphere components.

Since VMware has deprecated the Windows-based version of vCenter Server, it's worth migrating directly to the Linux-based vCSA. This takes advantage of the new features that were introduced in version 6.5, such as embedded VUM, vCenter High Availability (VCHA), and built-in file-based backup restore, which is available in the vCSA only. If you have vCenter Servers with external Platform Services Controllers (PSCs), get both components on the same version to take advantage of new features.

You can perform an upgrade of vCSA 6.5 to 6.7 using the following tools:

• Graphical interface: Using this, you can insert the new vCSA ISO image into your management station as well as by using guided installation
• CLI interface: On the vCSA ISO file, you can also find the CLI that allows you to upgrade vCSA in unattended mode

When PSCs and vCenter Servers have been upgraded, you can start migrating ESXi hosts. ESXi 5.5 is not supported in version 6.7 at all, so you must upgrade those ESXi hosts before managing them through vCenter 6.7. ESXi 6.0 or 6.5 can be managed by vCenter 6.7, although new features won't be available for such hosts.