Omniauth facebook authentication failure Invalid application Id - ruby-on-rails

Question

I am using omniauth-facebook gem to authorize using facebook in my rails application.
I have followed these instructions but the problem I am facing is error about invalid credentials:
(facebook) Authentication failure! invalid_credentials: OAuth2::Error, :
{"error":{"message":"Error validating application. Invalid application ID.","type":"OAuthException","code":101}}
What is weird about this is that I am getting user info even though I get this error from facebook api.
the value of request.env['omniauth.auth']
is(server log).
#<OmniAuth::AuthHash credentials=#<OmniAuth::AuthHash expires=true
expires_at=1421256863 token="some_long_value"> extra=#<OmniAuth::AuthHash
raw_info=#<OmniAuth::AuthHash education=[#<OmniAuth::AuthHash school=
#<OmniAuth::AuthHash id="174179219354091" name="Udacity"> type="College">]
email="ashish#gmail.com" favorite_athletes=[#<OmniAuth::AuthHash id="51926382304"
name="Derrick Rose">, #<OmniAuth::AuthHash id="344128252278047" name="Sachin
Tendulkar">,.... so on
routes.rb
devise_for :users, :controllers => {:omniauth_callbacks => "omniauth_callbacks"}
config/initializers/omniauth.rb
OmniAuth.config.logger = Rails.logger
Rails.application.config.middleware.use OmniAuth::Builder do
provider :facebook, 'key', 'secret', {:provider_ignores_state => true}
# key and secret are correctly added in above line
end
app/model/user.rb
devise :omniauthable, :omniauth_providers => [:facebook]
app/controller/omniauth_callback_controller.rb
class OmniauthCallbacksController < Devise::OmniauthCallbacksController
def facebook
omniauth = request.env['omniauth.auth']
# Other code to create authentication and other logic
puts "===>>> Omniauth is #{omniauth}"
end
def failure
res = request.env['omniauth.auth']
puts "======>>>>>> Authentication failed #{res}"
redirect_to root_path
end
end
Every time response goes to failure method but not to facebook method.
What I don't understand is when I am getting invalid credentials error from api then how come I get all the data from facebook. I doubt I have something wrong on my end while handling the callback from facebook.
Can anyone point where the problem can be?
I am pretty sure I am using correct application id and key I am getting data from facebook in the response.
Can anybody help me with this issue?