1. 备份原来的源

   sudo cp /etc/apt/sources.list /etc/apt/sources_init.list

2. 更换源

   sudo gedit /etc/apt/sources.list

• 阿里源

  deb http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
  deb http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
  deb http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
  deb http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse
  deb http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse
  deb-src http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
  deb-src http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
  deb-src http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
  deb-src http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse
  deb-src http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse

• 中科大源

  deb https://mirrors.ustc.edu.cn/ubuntu/ bionic main restricted universe multiverse
  deb-src https://mirrors.ustc.edu.cn/ubuntu/ bionic main restricted universe multiverse
  deb https://mirrors.ustc.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse
  deb-src https://mirrors.ustc.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse
  deb https://mirrors.ustc.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse
  deb-src https://mirrors.ustc.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse
  deb https://mirrors.ustc.edu.cn/ubuntu/ bionic-security main restricted universe multiverse
  deb-src https://mirrors.ustc.edu.cn/ubuntu/ bionic-security main restricted universe multiverse
  deb https://mirrors.ustc.edu.cn/ubuntu/ bionic-proposed main restricted universe multiverse
  deb-src https://mirrors.ustc.edu.cn/ubuntu/ bionic-proposed main restricted universe multiverse

• 163源

  deb http://mirrors.163.com/ubuntu/ bionic main restricted universe multiverse
  deb http://mirrors.163.com/ubuntu/ bionic-security main restricted universe multiverse
  deb http://mirrors.163.com/ubuntu/ bionic-updates main restricted universe multiverse
  deb http://mirrors.163.com/ubuntu/ bionic-proposed main restricted universe multiverse
  deb http://mirrors.163.com/ubuntu/ bionic-backports main restricted universe multiverse
  deb-src http://mirrors.163.com/ubuntu/ bionic main restricted universe multiverse
  deb-src http://mirrors.163.com/ubuntu/ bionic-security main restricted universe multiverse
  deb-src http://mirrors.163.com/ubuntu/ bionic-updates main restricted universe multiverse
  deb-src http://mirrors.163.com/ubuntu/ bionic-proposed main restricted universe multiverse
  deb-src http://mirrors.163.com/ubuntu/ bionic-backports main restricted universe multiverse

• 清华源

  deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic main restricted universe multiverse
  deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic main restricted universe multiverse
  deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse
  deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-updates main restricted universe multiverse
  deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse
  deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-backports main restricted universe multiverse
  deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-security main restricted universe multiverse
  deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-security main restricted universe multiverse
  deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-proposed main restricted universe multiverse
  deb-src https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ bionic-proposed main restricted universe multiverse

3. 更新

更新源

sudo apt-get update

复损坏的软件包，尝试卸载出错的包，重新安装正确版本的。

sudo apt-get -f install

更新软件

sudo apt-get upgrade