Symptoms

Upgrade fails during vCenter Dry-Run Prechecks.When checking the vCenter virtual machine (VM) settings, you find the CD/DVD Drive is missing (not visible).

Cause

This issue usually occurs when the vCenter VM had an ISO image attached previously and then it was detached but not removed. 

Resolution

Open ESXi UI for the node that the vCenter VM is running on (https://<ESXi_IP>/ui).Locate the vCenter VM and power it off (Shutdown Guest Operating System).Click Add other device, choose CD/DVD Drive, then click Save.Power on the vCenter VM.Wait until all vCenter services are up, then retry the upgrade.

Support Cases