sudo apt-get update
Hit:1 http://security.ubuntu.com/ubuntu bionic-security InRelease
Hit:2 http://archive.ubuntu.com/ubuntu bionic InRelease
Ign:3 http://archive.ubuntu.com/ubuntu disco InRelease
Hit:4 http://archive.ubuntu.com/ubuntu bionic-updates InRelease
Err:5 http://archive.ubuntu.com/ubuntu disco Release
404 Not Found [IP: 91.189.88.142 80]
Reading package lists... Done
E: The repository 'http://archive.ubuntu.com/ubuntu disco Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
W: Skipping acquire of configured file 'u/binary-i386/Packages' as repository 'http://archive.ubuntu.com/ubuntu bionic-updates InRelease' doesn't have the component 'u' (component misspelt in sources.list?)
W: Skipping acquire of configured file 'u/binary-amd64/Packages' as repository 'http://archive.ubuntu.com/ubuntu bionic-updates InRelease' doesn't have the component 'u' (component misspelt in sources.list?)
W: Skipping acquire of configured file 'u/i18n/Translation-en' as repository 'http://archive.ubuntu.com/ubuntu bionic-updates InRelease' doesn't have the component 'u' (component misspelt in sources.list?)
W: Skipping acquire of configured file 'u/i18n/Translation-en_US' as repository 'http://archive.ubuntu.com/ubuntu bionic-updates InRelease' doesn't have the component 'u' (component misspelt in sources.list?)
W: Skipping acquire of configured file 'u/dep11/Components-amd64.yml' as repository 'http://archive.ubuntu.com/ubuntu bionic-updates InRelease' doesn't have the component 'u' (component misspelt in sources.list?)
W: Skipping acquire of configured file 'u/dep11/icons-48x48.tar' as repository 'http://archive.ubuntu.com/ubuntu bionic-updates InRelease' doesn't have the component 'u' (component misspelt in sources.list?)
W: Skipping acquire of configured file 'u/dep11/icons-64x64.tar' as repository 'http://archive.ubuntu.com/ubuntu bionic-updates InRelease' doesn't have the component 'u' (component misspelt in sources.list?)
W: Skipping acquire of configured file 'u/cnf/Commands-amd64' as repository 'http://archive.ubuntu.com/ubuntu bionic-updates InRelease' doesn't have the component 'u' (component misspelt in sources.list?)
我的 /etc/apt/sources.list
deb http://archive.ubuntu.com/ubuntu bionic main universe multiverse restricted
deb http://security.ubuntu.com/ubuntu/ bionic-security main multiverse universe restricted
deb http://archive.ubuntu.com/ubuntu disco main multiverse universe restricted
deb http://archive.ubuntu.com/ubuntu bionic-updates main multiverse u
答案1
你必须重命名迪斯科（19.04，EOL）支持更正条目仿生的(18.04 LTS，免费支持到2023年)。
打开终端并执行：
sudo sed -i "s/disco/bionic/g" /etc/apt/sources.list
然后修复损坏的行main multiverse u经过
sudo sed -i "s/main multiverse u$/main multiverse universe restricted/g" /etc/apt/sources.list
然后sudo apt-get update再次运行。
下一个建议的步骤是通过 安装所有具有最新依赖项的升级sudo apt-get dist-upgrade。
值得阅读的好资源——man sources.list本地或在线的。