环境 ubuntu 19.04
日期2020/04/18
更新软件失败，以为是源的问题 ，所以尝试 修改 源为 国内阿里源
查看 系统版本
lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 19.04
Release: 19.04
Codename: disco
其中的codename是这个版本的系统别名
查看阿里源
http://mirrors.aliyun.com/ubuntu/dists/
发现如下内容，以为支持，所以更换阿里源
disco/ 14-Apr-2020 20:23 - disco-backports/ 14-Apr-2020 20:24 - disco-proposed/ 14-Apr-2020 20:24 - disco-security/ 14-Apr-2020 20:24 - disco-updates/ 14-Apr-2020 20:23 -
结果报错，阿里源 也不是所有版本都支持
Ign:1 http://mirrors.aliyun.com/ubuntu/dists artful InRelease
Ign:2 http://mirrors.aliyun.com/ubuntu/dists artful-security InRelease
Ign:3 http://mirrors.aliyun.com/ubuntu/dists artful-updates InRelease
Ign:4 http://mirrors.aliyun.com/ubuntu/dists artful-backports InRelease
Ign:5 http://mirrors.aliyun.com/ubuntu/dists artful-proposed InRelease
Err:6 http://mirrors.aliyun.com/ubuntu/dists artful Release
404 Not Found [IP: 183.240.176.117 80]
Err:7 http://mirrors.aliyun.com/ubuntu/dists artful-security Release
404 Not Found [IP: 183.240.176.117 80]
Err:8 http://mirrors.aliyun.com/ubuntu/dists artful-updates Release
404 Not Found [IP: 183.240.176.117 80]
Err:9 http://mirrors.aliyun.com/ubuntu/dists artful-backports Release
404 Not Found [IP: 183.240.176.117 80]
Err:10 http://mirrors.aliyun.com/ubuntu/dists artful-proposed Release
404 Not Found [IP: 183.240.176.117 80]
Reading package lists... Done
E: The repository ‘http://mirrors.aliyun.com/ubuntu/dists artful 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://mirrors.aliyun.com/ubuntu/dists artful-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://mirrors.aliyun.com/ubuntu/dists artful-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://mirrors.aliyun.com/ubuntu/dists artful-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.
E: The repository ‘http://mirrors.aliyun.com/ubuntu/dists artful-proposed 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.
19.04这个版本 已经不支持了，所以更改，源文件的地址为
deb http://cn.archive.ubuntu.com/ubuntu/
deb http://old-releases.ubuntu.com/ubuntu/
之后 sudo apt update,就可以正常使用了。
原文：https://www.cnblogs.com/zhaoxizhong/p/12727289.html