问题：错误 404 代码状态http://archive.ubuntu.com/ubuntu cosmic InRelease
Ubuntu 18.10 宇宙生命终结
从昨天开始，apt install 命令不再起作用，我尝试升级我的系统版本，但我得到了与 apt-get update 命令相同的错误
$ apt update
Ign:1 http://archive.ubuntu.com/ubuntu cosmic InRelease
Ign:2 http://security.ubuntu.com/ubuntu cosmic-security InRelease
Ign:3 http://archive.ubuntu.com/ubuntu cosmic-updates InRelease
Ign:4 http://archive.ubuntu.com/ubuntu cosmic-backports InRelease
Err:5 http://security.ubuntu.com/ubuntu cosmic-security Release
404 Not Found [IP: 91.189.88.173 80]
Err:6 http://archive.ubuntu.com/ubuntu cosmic Release
404 Not Found [IP: 91.189.88.31 80]
Err:7 http://archive.ubuntu.com/ubuntu cosmic-updates Release
404 Not Found [IP: 91.189.88.31 80]
Err:8 http://archive.ubuntu.com/ubuntu cosmic-backports Release
404 Not Found [IP: 91.189.88.31 80]
Reading package lists... Done
E: The repository 'http://security.ubuntu.com/ubuntu cosmic-security 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.
E: The repository 'http://archive.ubuntu.com/ubuntu cosmic 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.
E: The repository 'http://archive.ubuntu.com/ubuntu cosmic-updates 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.
E: The repository 'http://archive.ubuntu.com/ubuntu cosmic-backports 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.