Thumbnail Unauthorized Access

Suspected new update causing error to the thumbnail in Facebook that displays Unauthorized Access. But, when clicked still point to the correct page.

Tested the link, http://www.langitilahi.com/cerpen-buah-pinggang/ on Facebook Debugger, https://developers.facebook.com/tools/debug/sharing/

Got this error:
Inferred Property
The ‘og:image’ property should be explicitly provided, even if a value can be inferred from other tags.

Missing Properties
The following required properties are missing: og:url, og:type, og:title, og:image, og:description, fb:app_id

Appreciate your kind advice. Thank you.

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