I recently received the following Facebook developer alert:
Version v2.9 upgrade reminder
Learn Moodle and 2 other apps currently have access to Graph API v2.9 which will reach the end of its 2-year lifetime on 22 July, 2019.We estimate 3 endpoints in total will be impacted by this change and may stop working after the automatic upgrade push. To ensure a smooth transition, please migrate all calls to Graph API v2.10 or higher. Use the API Upgrade Tool to understand exactly how this change will impact your app.