Basic source lookup: Internal Server Error

Basic source lookup is not working with my Snorby 2.6.3 installation, here is the ouput generated in production.log:

Started GET "/events/lookup?address=xx.xx.xx.xxx" for 192.168.100.1 at 2016-03-30 11:46:22 +0200
Processing by EventsController#lookup as HTML
  Parameters: {"address"=>"xx.xx.xx.xx"}
  Rendered events/lookup.html.erb (221.2ms)
Completed 500 Internal Server Error in 235.3ms

ActionView::Template::Error (uninitialized constant Config):
    8: 
    9:          <pre id='whois' class='query-data-content'><%= @lookup.whois %></pre>
    10:                 
    11:                 <pre id='dns' class='query-data-content' style='display:none;'><%= @lookup.dns %></pre>
    12: 
    13:         </div>
    14: 
  lib/snorby/lookup.rb:25:in `dns'
  app/views/events/lookup.html.erb:11:in `block in _app_views_events_lookup_html_erb___1498975319660734606_7979024527540'
  app/helpers/application_helper.rb:161:in `snorby_box'
  app/views/events/lookup.html.erb:1:in `_app_views_events_lookup_html_erb___1498975319660734606_7979024527540'
  app/controllers/events_controller.rb:335:in `lookup'

Snorby / snorby

Basic source lookup: Internal Server Error #427