我不明白为什么它不起作用。Ubuntu 18.04 应该支持到 2028 年 4 月
apt-get 更新
Hit:1 http://archive.ubuntu.com/ubuntu bionic InRelease
Hit:3 http://archive.ubuntu.com/ubuntu bionic-updates InRelease
Hit:4 http://archive.ubuntu.com/ubuntu bionic-backports InRelease
Ign:2 https://security.ubuntu.com/ubuntu bionic-security InRelease
Err:5 https://security.ubuntu.com/ubuntu bionic-security Release
404 NOT FOUND [IP: 91.189.88.181 443]
Reading package lists... Done
E: The repository 'http://security.ubuntu.com/ubuntu bionic-security Release' no longer has 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.
lsb_发布-a；
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 18.04.5 LTS
Release: 18.04
Codename: bionic