Error parsing input URL, no data was cached, or no data was scraped.

https://www.thearmchaircritic.org
This is my website and I had no problems sharing my posts across various social media sites.
But recently, I realized that the links shared in Facebook nor more have the featured image in them. So I did a bit of research and found the debugger tool of facebook which gives me the error message, “Error parsing input URL”.

Not only Facebook, but Twitter and Google+ are also unable to extract the rich content of my website.

I am using Yoast SEO plugin and tried Jetpack’s open graph tags too to no avail.

However, certain pages of my site are working properly, viz., https://www.thearmchaircritic.org/ and https://www.thearmchaircritic.org/poems/a-paladin-rising-from-the-corpses-a-poem-for-sanga

The version of my wordpress installation is 4.2.2 and I have tried disabling all the plugins, tried using a different theme but all have been in vain.

I am hosting a couple more sites and they are functioning well, which means the host has no problem.

ANy help would be very much appreciated!