Hi @seetal, welcome to the forum! We're glad you're here. When you get a chance, please introduce yourself on this other forum thread. I'd also encourage you to add a real picture as your avatar because it helps build community!
I had better luck with installing on an Ubuntu 16.04 server; I wonder if that would make a difference. Are there any other error messages? Could you try rebooting the whole server and see if backups work after that?