Troubleshooting the zeus gem

First, try to run a regular command like rails s or bundle exec rake to see if there any issues with Rails itself and not zeus.

If the issue is clearly with zeus and for the open /dev/ptmx: device not configured error do a:

  $ sudo killall -9 ruby
  $ zeus start

One time I just had to kill a console window where I was running the zeus. Next, I started a new console window and then ran zeus start.