When I post a k2 article link on facebook it includes the article image but instead of intro text there is error code. See attached image and advise on how to solve this problem.

It seems that you are injecting the share this code in your full text.
That is why it is displaying in your FB posts.

I didn't inject anything. But I have since disabled the sharethis plugin which displayed on top of all articles and I am still having the same problem.

maybe its a browser cookie thing. I'm going to clean cookies and see if it happens again.

FB also caches its results.
Even if you have removed that plugin and cleaned its code you should allow some time for FB to recrawl your site.

Krikor Boghossian wrote: It seems that you are injecting the share this code in your full text.
That is why it is displaying in your FB posts.

I had a ShareThis plugin installed. It worked fine 1st September 2014. The only change I made was for it to display above articles instead underneath. I have disabled it.

The sharethis images no longer appear under or above articles but I still have the same problem. Plus now the facebook link will no longer display article image thumbnail. Things have gone from bad to worse.
This is an unexpected problem.

The whole point of creating the website was for posting articles to facebook and now this?

How long before facebook refresh? I'm trying post a timely tribute and this is screwing up my game. Literally!

Also what do i do about the missing thumbnail?

I am not sure. You can use developers.facebook.com/tools/debug/ to check your URLS and refetch content.

As for the thumbnail make sure that it is at least 200px in both dimensions.