Meta - Add Facebook app id meta property to fix 'the following required properties are missing: fb:app_id'

Question

You'll get this issue upon debugging the page with Facebook sharing debugger here: https://developers.facebook.com/tools/debug/ - with the error message of 'the following required properties are missing: fb:app_id'  To fix:

1. Inspect element to check whether the meta property for fbapp_id is exist on your site. If not, add the following code to your site header. 

2. <meta property="fb:app_id" content="ХХХХХХХХХХХХХХХ" /> 

3. Get the fb id from here: https://developers.facebook.com/apps/  .example as follows:
4. and replace the content="ХХХХХХХХХХХХХХХ" value with your fb ids