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.
2. In your apps dashboard, click Create App button.
3. Choose the Consumer app type and click Continue.
4. Type your app name (it will be visible for users), email address (for notifications from Facebook) and click Create App:
5. After the app gets created you will get redirect to the app edit screen, click Settings -> Basic in the menu at left:
6. 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:
7. Fill the form Data Protection Officer Contact Information below if required according to your business:
8. Click on Add Platform after the forms:
9. Select Website:
10. Specify an URL of your website and save the changes:
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.