Ref: Facebook Link Ownership Guide
On November 7, 2017, Facebook released a new API version, 2.11. It includes an additional restriction to publish posts only from the authors who own a Page and an associated domain.
There are two alternatives to verify the ownership of a domain and an associated page:
Domain Verification: Domain Verification provides a way for you to claim ownership of your domain in Business Manager. This ownership allows you to control editing privileges of your links and other content to prevent misuse of your domain and to keep bad actors from spreading misinformation. For more information: https://developers.facebook.com/docs/sharing/domain-verification. The new domain verification in Facebook's Business Manager is a free operation of the platform to manage Business pages.
The new Business Manager is the new area for managing assets in Facebook Platform. In our experience, it is going to become the "only way" to manage Pages in Facebook terms.
Be sure to correctly associate your Pages and People, check if the users are correctly added to the Business Manager/Business Settings/Accounts/Pages/People. Once it is done, perform a full re-authorization.
Open Graph Tags: The plugin AutoTweet Facebook OpenGraph Tags plugin allows to define the pages IDs associated with your site. For more information: https://www.extly.com/docs/autotweetng_joocial/installation/open-graph-tags#auto-tweet-facebook-open-graph-tags-plugin
Any of these method can be used to verify the ownership. If you opt to implement the AutoTweet Facebook OpenGraph Tags plugin, the Page ID can be found here:
To access your Facebook's Page ID:
After you identify the ownership of your domain, you must re-authorize the Facebook channel.
To confirm that the Open Graph Tags are correctly defined and accepted by Facebook, please, check the article page on Facebook sharing Debugger: https://developers.facebook.com/tools/debug/sharing/
This is how Facebook presents the ideal case https://developers.facebook.com/docs/sharing/webmasters#testing:
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