ESXi: The operation is not allowed in the current state

Today I stepped into this issue while trying to vMotion a VM to another host. When validating destination host this error is displayed:

The operation is not allowed in the current state

After a brief search I found KB 1003829 which states:

1)Cancel the Enter maintenance mode
My host was not entering maintenance mode

2)Restart the ESX host's management agents
Done but still got error

3)Wait until any pending tasks for the ESX host are complete
No running tasks reported from vSphere Client. Logged into my host using SSH to see if there are pending tasks using this command:

vim-cmd vimsvc/task_list

# vim-cmd vimsvc/task_list
(ManagedObjectReference) [
   'vim.Task:haTask-5-vim...'
]
There was a task still running due to the command above (if there are no ongoing tasks the brackets "[]" are empty), waited until completion but vMotion host validation still failed with message "The operation is not allowed in the current state".

4.a)Disconnect and then reconnect the ESX host to VirtualCenter
Done but still got error

4.b)Restart the VMware VirtualCenter Server service
Finally here is how I solved my issue!

To restart vCenter Server go to:

https://YOUR_VCENTER_SERVER:5480

Click Stop button and wait until services stopping occurs.

Then cick Start and wait for completion.

After this I was able to correctly vMotion guest VMs!!