Facebook API since October 1st, 2018 requires a mandatory App ID in order to continue using their Share/Recommend buttons events (essential to allow Social Share meet when an user performs those actions).
If you want to use these buttons, you need to register a Facebook App for your website.
1. Open the website developers.facebook.com and click Add a New App (you have to be logged in):
2. Type your app name (it will be visible for users), email address (for notifications from Facebook) and click Create App ID:
3. Pass the security check if required and click on Submit:
4. Click Settings -> Basic in the menu at the left:
5. Twice enter your site domain name (without “www” and with “www” if your are using this subdomain), check your email address, select the category and paste links to Terms & Policy pages:
6. Fill the form Data Protection Officer Contact Information below if required according to your business:
7. Click on Add Platform after the forms:
8. Select Website:
9. Specify an URL of your website and save the changes:
10. Move to the section App Review:
11. Make your app available to the general public:
12. Copy your app ID:
13. Paste your Facebook App ID on the page GamiPress -> Settings -> Add-ons -> Social Share -> Facebook.
That’s all! Now Social Share will use your Facebook App ID to load the facebook buttons.