Stopped working but is fixable

This plugin was working fine for me until recently when it developed the error listed by bhupendraosd and whiteriverdesign. Not sure at which of the recent WordPress updates the problem started.

I was using this plugin without creating a Facebook App ID and App Secret but, having browsed the discussion at https://www.ads-software.com/support/topic/facebook-api-came-back-with-a-faulty-result
I tried creating a App ID as described there and, lo and behold, it has fixed my problem.