Re: Hi..When we have try to power off the VM. We are getting the below error info " failed to dispatch event {0}. We unable to power off the VM.

are there any other errors you are aware of?  e.g. login as system admin -> manage/monitor -> cells ... this sounds like we are failing to communicate with vCenter in a general sense.  Power toggles (on or off) are a pretty basic API call to vCenter itself, and I haven't really seen it fail in the 4 years I've worked with vCloud Director.