Error: No access to this page. Make sure that you are an administrator of the page and that you have granted our application rights to this page when authorizing via Facebook.

This error can be seen in the Facebook account settings.

It occurs when the user through whom the account was connected to the service is no longer an administrator of the Facebook page.
In this case, you need to reauthorize in the account settings in theSettings - Social profiles sectionusing the user who has administrator rights on Facebook.