@naturevj I'm not sure but I think it's due to 1.8.9 is still probably still in beta. If I remember correctly 1.8.9 and 1.9 is still in beta that why it's still unstable. I think you'll have to wait until a dev, admin, or moderator responds with more info. You can still continue using it at your own risk but sadly I have no info on that version.
It's not related to 1.8.9. It's because they are using a cracked launcher. Following this will solve the issue: https://discuss.aristois.net/topic/23/