Hello @JoeKun my team is also seeing similar issues. We are doing a POST on the following endpoint: https://api.music.apple.com/v1/me/library/playlists/%s/tracks with the following as the payload: { "data": [{"id": track_id, "type": "song"}, ....] } I am seeing an internal server error Internal Server Error: Upstream Service Error-Unable to update tracks and here is the full response content: {"errors":[{"id":"BEVQOFCT3F2OM3I7NBLJKAFI54","title":"Upstream Service Error","detail":"Unable to update tracks","status":"500","code":"50001"}]} I think you can leverage the error ID to check on your end? Could you help check on your end if the account that we are attempting to update the playlist is having the same data issue that other people on this thread was seeing?