If you've received a facebook migration notice like the one below

Your app, "YourAppName" has not enabled the migration for the July 2013 Breaking Changes.
Once you have confirmed your app is compliant or unaffected by the July 2013 Breaking Changes, set the migration setting to "Enabled" in the Advanced section of the App Dashboard. This will apply the July 2013 Breaking Changes to your app and prevent you from receiving future alerts about these changes.
"YourAppName", is currently using the following deprecated features:
  • Social Plugins (Like Button, Like Box) without absolute URL's in their `href` parameter.
These changes will be permanently enabled for all apps in 72 days on Wednesday, July 10, 2013.
You can view this and other Developer Notifications related your app, YourAppName, in the App Dashboard.
Thanks,
The Facebook Team

The message above is a notification for your facebook application that might be affected with the changes that facebook will apply on the said date. Since HC is not using the deprecated feature it's okay to disregard this message.

This is the full document on the migration for facebook app: https://developers.facebook.com/roadmap/migrations/