If you are doing migration from v2.2.x to v3.0.0
You need to do the following changes.
Download SDK: https://github.com/facebook/facebook-php-sdk
Keep the two classes base_facebook.php and facebook.php with the certificate fb_ca_chain_bundle.crt
1. Create a Facebook Application by using your ‘Facebook Developer account’
2. Get the ‘App ID’ and ‘App Secret’ of your created application
Add following gems to your Gemfile