1.sudo vi/etc/apt/sources.list
2. Replace
#Deb Cdrom:[ubuntu 16.04 LTS _xenial xerus_-Release amd64 (20160420.1)]/xenial main restrictedDEB-SRC Http://archive.ubuntu.com/ubuntu xenial Main restricted#Added by Software-propertiesDeb http://mirrors.aliyun.com/ubuntu/xenial main Restricteddeb-SRC http://mirrors.aliyun.com/ubuntu/xenial main restricted Multiverse universe#Added by Software-propertiesDeb http://mirrors.aliyun.com/ubuntu/xenial-Updates main Restricteddeb-SRC http://mirrors.aliyun.com/ubuntu/xenial-updates main restricted Multiverse universe#Added by Software-propertiesDeb http://mirrors.aliyun.com/ubuntu/xenial universedeb http:mirrors.aliyun.com/ubuntu/xenial-Updates Universedeb http:mirrors.aliyun.com/ubuntu/xenial multiversedeb http:mirrors.aliyun.com/ubuntu/xenial-Updates Multiversedeb http:mirrors.aliyun.com/ubuntu/xenial-backports main restricted universe Multiversedeb-SRC http://mirrors.aliyun.com/ubuntu/xenial-backports main restricted universe multiverse#Added by Software-propertiesDeb http://archive.canonical.com/Ubuntu xenial Partnerdeb-SRC http://archive.canonical.com/Ubuntu xenial partnerdeb http:mirrors.aliyun.com/ubuntu/xenial-Security Main Restricteddeb-SRC http://mirrors.aliyun.com/ubuntu/xenial-security main restricted Multiverse universe#Added by Software-propertiesDeb http://mirrors.aliyun.com/ubuntu/xenial-Security Universedeb http:Mirrors.aliyun.com/ubuntu/xenial-security Multiverse
3. Update
sudo apt-get update
Ubuntu16.04lts Replacement Ali