installed vagrant-aws & vagrant-cloudstack.
dependency fog version.

 INFO manager: Registered plugin: AWS
 INFO environment: Loading plugin from JSON: vagrant-cloudstack
ERROR root: Failed to load plugin: vagrant-cloudstack
ERROR root:  -- Error: #<Gem::LoadError: Unable to activate vagrant-cloudstack-0.1.0, because fog-1.15.0 conflicts with fog (~> 1.18.0)>
ERROR root:  -- Backtrace: