I\'m working on logging in a site via existing facebook
account. So I registered a facebook application and stored api and secret
I solved this issue when I deleted 'omniauth.rb' because I already have this config below in devise.rb:
config.omniauth :facebook, ENV["FB_ID"], ENV["FB_SECRET"],
scope: 'email',
info_fields: 'email, first_name, last_name',
image_size: 'large', # 50x50, guaranteed ratio
secure_image_url: true
Remember to restart the sever to test.