Omniauth-facebook keeps reporting invalid_credentials

I am trying to implement omniauth-facebook as described in Railscast #360 and have run into quite a roadblock. When I click on the signin link, I get the desired popup asking me to input my facebook credentials, but when I submit, I get an OmniAuth::Strategies::OAuth2::CallbackError error. In the apache logs, this is printed: (facebook) Authentication failure! invalid_credentials: OmniAuth::Strategies::OAuth2::CallbackError, OmniAuth::Strategies::OAuth2::CallbackError here is the relevant code: omniauth.rb ``` OmniAuth.config.logger = Rails.logger Rails.application.config.middleware.use OmniAuth::Builder do provider :facebook, ENV['FACEBOOK_APP_ID'], ENV['FACEBOOK_SECRET'] end ``` sessions_controller.rb ``` class SessionsController < ApplicationController def create user = User.from_omniauth(env["omniauth.auth"]) session[:user_id] = user.id redirect_to root_url end def destroy session[:user_id] = nil redirect_to root_url end end ``` application.html.erb ``` <div id="fb-root"></div> <script> window.fbAsyncInit = function() { FB.init({ appId : '(**my app id**)', // App ID status : true, // check login status cookie : true // enable cookies to allow the server to access the session }); $('#sign_in').click(function(e) { e.preventDefault(); return FB.login(function(response) { if (response.authResponse) { return window.location = '/auth/facebook/callback'; } }); }); return $('#sign_out').click(function(e) { FB.getLoginStatus(function(response) { if (response.authResponse) { return FB.logout(); } }); return true; }); }; </script> ``` Am I missing something simple? I've been searching for a solution for the last few days.