The social network said in a post on its developer blog that its request is not a breaking change, and existing custom actions are grandfathered in, but new ones should adhere to its request. More from the blog post:
Since we launched open graph nearly one year ago, actions that express affinity have become one of the most popular custom action types. Millions of people “favorite,” “heart,” and “love” experiences in applications daily and share these stories back to Facebook. We strongly encourage you to use the built-in like action for these relationships where possible. However, if you want to use custom verbiage to express affinity, you must now associate these actions with the built-in like action to ensure that we’re displaying these important relationships prominently across Facebook. For example, when SlideShare defines a custom action to help people indicate that a presentation is their favorite, they must associate it with the built-in like action.
By associating these actions with the built-in like action, we are better able to understand the nature of the stories users are telling, and present stories in engaging and consistent ways across news feed and timeline.
This is not a breaking change. You can continue to publish any current custom actions that express affinity. However, you must associate actions expressing affinity with the built-in like action when creating new custom actions or resubmitting existing actions with new changes. For example, when submitting a new “love” custom action, you must associate the action with the built-in like action.
To learn more, please see our documentation.