You don’t have permission to access /wp-admin/post.php on this server.

Hi,
I was getting the following error, whenever i was trying to save post,
“You don’t have permission to access /wp-admin/post.php on this server.”
This error came with a blank screen and with the heading “Forbidden”. However the post it self saves.
screenshot: https://i.imgur.com/xcj8psN.png

First i thought post.php did not have the right permissions assigned to access it, then after having a look at the permissions they turned out to be just fine.
After a lot of digging, headache and frustration i finally found that your plugin was causing the problem. Digging further into your plugin’s code the core of problem was in file: class-webdados-fb-open-graph-admin -line 30.
The line was returning the error due to unavailability of APP ID and App secret for clear caching option. Your plugin, instead of showing me some sort of warning, it was breaking my site.

I would really appreciate if you kindly sort this problem for the users how have knowing or mistakenly selected Clear Caching option but did not provided any App ID for it.