Facebook Permissions Error - Could Not Share Post
What Caused The Post To Fail
This happens if you are trying to share a link to an existing Facebook post, but the privacy settings for that post prevent it from being shared on your profile or page.
In order to re-share any Facebook content to your profile/page, that content must be public.
How To Resolve
If you are the owner of that content, please check the privacy settings for the post, and ensure that it is visible to the public.
Sometimes there may be age-related, or country-related, restrictions which prevent the content from being fully public.