Hello.
Note: This discussion was moved from the VMware vCenter Server community to the Availability: HA & FT community.
Check out kb 1025235.
Good Luck!
Noted. Unfortunately, while there is no error message when I access thru VI Client 4.0, I am not allow to update the HA configuration as it appears to be disabled and cannot be configured with EVC mode since there are powered on VMs running. When I access thru VI Client 4.1, the error message is still there.