Facebook has updated the Graph API to version v2.1, making significant changes to how some of the API calls work while deprecating other features. The current Facebook PHP SDK stable version is still v4.0.9 and uses Graph API v2.0, but PHP SDK v4.1 will eventually make use of Graph API v2.1.
Facebook API: Graph API v2.1 Now Available, ‘Likegates’ No Longer Allowed
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