VMware recently announced vSphere 6.5 release. Dell supports direct upgrade to Dell customized ESXi 6.5 from both ESXi 6.0 Update 2 and ESXi 5.5 Update 3 branches. This document talks about some of the best practices to be considered before upgrading to Dell customized ESXi 6.5 in terms of UEFI Secureboot. This white paper is relevant for all users who plan to migrate to Dell customized version of VMware ESXi 6.5 and make use of UEFI secureboot feature. The paper can be downloaded from here and is also attached with this blog. 

This upgrade guide covers the recommendations on enabling UEFI secureboot specific to relevant upgrade scenarios to ESXi 6.5. Prior to enable UEFI secureboot on an upgraded system, it's highly recommended to go through this white paper and understand the caveats. These caveats are not applicable for a fresh install of Dell customized VMware ESXi 6.5 as it contains all compatible VIBs for UEFI secureboot.