Description of problem:

When an user tries to open console of a VM in User Portal which was stopped but User Portal has not refresh the VM status yet, the user sees in User Portal:

Operation Cancelled
'Error while executing action VmLogon: Internal Engine Error'

Version-Release number of selected component (if applicable):
rhevm-userportal-3.6.3.2-0.1.el6.noarch

How reproducible:
100%

Steps to Reproduce:
1. have an user and open a VM console in User Portal
2. login with another user which has rights to open same VM console
3. for the latter user change refresh time in User Portal to 60 secs
   (to ease refresh delay)
4. as the former user shutdown the VM
5. when the VM is down, as latter user (with "slow" refresh) observe the VM icon
   and it is allows to open console (thus VM status has not been refreshed yet),
   double click on the VM icon to open console
6. observe User Portal for popup window

Actual results:
Operation Cancelled
'Error while executing action VmLogon: Internal Engine Error'

Expected results:
human readable error msg

Additional info: