我尝试过使用sudo apt update && sudo apt upgrade.但它不起作用。
Hit:1 http://linux.*********r.com/deb stable InRelease
Hit:2 http://dl.google.com/linux/chrome/deb stable InRelease
Hit:4 http://archive.canonical.com/ubuntu xenial InRelease
Hit:5 http://old-releases.ubuntu.com/ubuntu disco InRelease *******
Ign:6 http://old-releases.ubuntu.com/ubuntu xenial InRelease
Hit:7 http://old-releases.ubuntu.com/ubuntu disco-updates InRelease****
Hit:8 https://repo.*****.com/deb stable InRelease
Ign:9 http://old-releases.ubuntu.com/ubuntu xenial-updates InRelease
Hit:10 http://old-releases.ubuntu.com/ubuntu disco-backports InRelease
Ign:11 http://old-releases.ubuntu.com/ubuntu xenial-backports InRelease
Hit:12 http://old-releases.ubuntu.com/ubuntu disco-security InRelease
Ign:13 http://old-releases.ubuntu.com/ubuntu xenial-security InRelease
Err:14 http://old-releases.ubuntu.com/ubuntu xenial InRelease
404 Not Found [IP: ****************]
Err:15 http://old-releases.ubuntu.com/ubuntu xenial-updates InRelease
404 Not Found [IP: ****************]
Err:16 http://old-releases.ubuntu.com/ubuntu xenial-backports InRelease
404 Not Found [IP: ****************]
Err:17 http://old-releases.ubuntu.com/ubuntu xenial-security InRelease
404 Not Found [IP: ****************]
Get:3 https://mirrors.bfsu.edu.cn/****/systems/win32/******/setup/deb bionic InRelease [2,034 B]
Err:3 https://mirrors.bfsu.edu.cn/****/systems/win32/******/setup/deb bionic InRelease
The following signatures were invalid: EXPKEYSIG 277A7293F59E4889 ****** Packager <packager@******.org>
Reading package lists... Done
E: The repository 'http://old-releases.ubuntu.com/ubuntu xenial Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by defualt.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: The repository 'http://old-releases.ubuntu.com/ubuntu xenial-updates Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by defualt.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: The repository 'http://old-releases.ubuntu.com/ubuntu xenial-backports Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by defualt.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: The repository 'http://old-releases.ubuntu.com/ubuntu xenial-security Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by defualt.
N: See apt-secure(8) manpage for repository creation and user configuration details.
W: GPG error: https://mirrors.bfsu.edu.cn/****/systems/win32/******/setup/deb bionic InRelease: The following signatures were invalid: EXPKEYSIG 277A7293F59E4889 MiKTeX Packager <packager@******.org>
E: The repository 'http://**********/download/ubuntu bionic InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by defualt.
N: See apt-secure(8) manpage for repository creation and user configuration details.
无法下载更新：
刷新缓存失败：E：存储库“http:old-releases.ubuntu.com/ubuntu xenial Release”没有发布文件。
软件更新程序还提供了一个错误：
下载存储库信息失败
检查您的连接。
答案1
运行这个命令
sudo do-release-upgrade -d -f DistUpgradeViewGtk3
然后开始升级。