This error could point to the following issues:
  1. Go to Settings > Basic and make sure there is a Contact Email populated.
  2. Go to App Review and make sure your app is live (Your app is currently live and available to the public).
  3. On App Review, scroll down to make sure publish_actions is not included (As of August 1, 2018, Facebook no longer allows the publish_actions permission. If it is included, resubmit the app for review.).