VMware ESXi 6.5 Install/Upgrade step-by-step

In this post, we will discuss how to upgrade VMware ESXi 6.5 to 6.5 U1.

Difficulty Level: Intermediate

Introduction

It goes without saying how important it is to have a backup and the configuration of an ESXi host prior to following these steps if your goal is to rebuild an existing ESXi host. If you don't know how to back up an existing ESXi host, you can learn how in the following post: Backup and Restore the VMware ESXi 6.X Configuration.

Please review the VMware Compatibility Guide prior to following the below steps.

VMware ESXi 6.5 Installation

First things first, you need to download the VMware vSphere Hypervisor (ESXi ISO) image from the my VMware website. For this demonstration I will be installing the ESXi 6.5 U1 (Build 5969303). I have already mounted the ISO using iDRAC and rebooted the server to the Virtual CD. Though your environment may be different, you have many options available with the ISO--burning the ISO to CD/DVD, booting from it directly in a nested install configuration, or creating a bootable USB disk. 

Hit [Enter].

Accept and Continue by hitting [F11].

Select the disk to install or upgrade and hit [Enter].

Select the desired installation path and hit [Enter].

Acknowledge any Errors/Warnings and hit [Enter].

Hit [F11] to Upgrade.

The install begins!

After the installer completes, we are prompted to reboot by pressing [Enter]. Ensure any installation media is removed prior to rebooting.

After a successful reboot verify the correct Build Number. In our case, Build 5969303.

Conclusion

Though we did not experience any surprises with this upgrade I have seen rare instances in the past where an install or upgrade fails. In most cases, it is easier to start over from scratch instead of spending hours on end combing through Google search results or dealing with VMware support.

Remember, good and frequent configuration backups are your best friend.

Here are just two examples of a faulty ESXi install:

kernel=<FILEPATH> must be set in /boot.cfg
Fatal error: 32 (Syntax)

UnicodeDecodeError: 'ascii' codec can't decode byte 0xed in position 119: ordinal not in range(128)