The issue in this case was that the VMWare Directory Service (vmdir) was in a Read Only Mode as Support find out in the logs. This has happened during the earlier migration from a vCenter 5.5 Server to the appliance. You don't get a message or something related.
The solution was to set the vmdir to Normal mode by CLI and after that reboot the Appliance.
Can you give any further detail regarding how this was resolved? I'm not able to find a method for setting vmdir to Normal mode anywhere.
try this you should fix ...
I guess you did the license upgrade to cersion 6.x
I did see that article. Unfortunately, I'm running the appliance so I don't think that article applies.
I didn't understand your problem well. Have you already updated the vcenter? did you put the vcenter 6.x lincecza before updating the esxi hosts?
When does the update give you the error ??