In the morning I was trying to remove snapshot from VM using vSphere client, to my surprise, I couldn’t remove it. An error says:
Remove snapshot <VM name> Another task is already in progress. < domain\user> <virtual machine name> console
I tried to stop VM, without success, error this same like above.
Second try-out, from command line using vmware-cmd command with removesnpahots syntax, failed with error:
VMControl error -999: Unknown error: SoapError: ServerFaultCode(0) : (Operation failed since another task is in progress.)
I solved a problem by restarting vmware management agent on ESX host, # service mgmt-vmware restart. After process restart I was able remove snapshots and power VM down