Issue: Open Graph Object Debugger

Go to Home > Options > Facebook Options > Facebook Application ID to set the fb:app_id for your site.
VaultWiki generates the meta description of an article based on the first paragraph of text in the article. Since there are no paragraphs in this article, or the first paragraph is not significant, VaultWiki is unable to generate a usable description of the article. Instead, you should enter your own description:
There was a bug with the og:image property and that is now fixed.

Hi, the own description is for each page, or?It can be different ?

I set the fb:app_id and the error is still there on the object debugger.
And: there is now the standard og:image (set for XF), not the picture that is in the page... if there is a picture, it should be shown...???

Facebook will only use a random picture from the page if og:image is not specified; however if og:image is not specified, then Facebook considers it an error. So unfortunately that (the previous behavior which you correctly reported was invalid) cannot be the approach used. If you want a specific image used for og:image, you need to set that image as the article icon on the edit tab. Otherwise it will default to the site's og:image.