事情是如何开始的：
- 重新启动后发现 gnome 无法正常工作
- 找到登录终端，尝试运行
apt-get update，发现网络也无法正常工作 - 启动实时会话并进入我的启动卷以查看发生了什么
- 做了通常的事（
update，，，，）upgradeautoremoveautocleaninstall --fix-broken - 基本上，apt 似乎对我是否是 ubuntu3.8 或 ubuntu3.13 感到困惑，我不知道这意味着什么，也不知道它是如何发生的
root@ubuntu:/# apt-get update
Get:1 file:/var/cuda-repo-ubuntu2004-11-6-local InRelease
Ign:1 file:/var/cuda-repo-ubuntu2004-11-6-local InRelease
Get:2 file:/var/cuda-repo-ubuntu2004-11-6-local Release [564 B]
Get:2 file:/var/cuda-repo-ubuntu2004-11-6-local Release [564 B]
Get:3 https://nvidia.github.io/libnvidia-container/stable/ubuntu18.04/amd64 InRelease [1484 B]
Hit:4 https://download.docker.com/linux/ubuntu focal InRelease
Hit:5 https://repo.steampowered.com/steam stable InRelease
Hit:6 http://packages.microsoft.com/repos/code stable InRelease
Hit:7 http://us.archive.ubuntu.com/ubuntu focal InRelease
Hit:9 http://security.ubuntu.com/ubuntu focal-security InRelease
Hit:10 http://ppa.launchpad.net/c2d4u.team/c2d4u4.0+/ubuntu focal InRelease
Hit:11 http://ppa.launchpad.net/graphics-drivers/ppa/ubuntu focal InRelease
Fetched 1484 B in 1s (1073 B/s)
Reading package lists... Done
root@ubuntu:/# apt-get dist-upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
root@ubuntu:/# apt-get autoremove
Reading package lists... Done
Building dependency tree
Reading state information... Done
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
root@ubuntu:/# apt-get autoclean
Reading package lists... Done
Building dependency tree
Reading state information... Done
root@ubuntu:/# apt install --fix-broken ubuntu-desktop
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
ubuntu-desktop : Depends: gdm3 but it is not going to be installed
Depends: gnome-control-center but it is not going to be installed
Depends: gnome-settings-daemon but it is not going to be installed
Depends: gnome-shell but it is not going to be installed
Depends: gnome-shell-extension-appindicator but it is not going to be installed
Depends: gnome-shell-extension-desktop-icons but it is not going to be installed
Depends: gnome-shell-extension-ubuntu-dock but it is not going to be installed
Depends: nautilus but it is not going to be installed
Depends: pulseaudio
Depends: ubuntu-desktop-minimal but it is not going to be installed
Depends: ubuntu-release-upgrader-gtk but it is not going to be installed
Depends: ubuntu-session but it is not going to be installed
Depends: update-manager but it is not going to be installed
Recommends: gnome-disk-utility but it is not going to be installed
Recommends: gnome-initial-setup but it is not going to be installed
Recommends: gvfs-fuse but it is not going to be installed
Recommends: nautilus-share but it is not going to be installed
Recommends: plymouth-theme-spinner but it is not going to be installed
Recommends: pulseaudio-module-bluetooth but it is not going to be installed
Recommends: usb-creator-gtk but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
root@ubuntu:/# apt-get install gdm3
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
gdm3 : Depends: gnome-settings-daemon (>= 3.24) but it is not going to be installed
Depends: gnome-shell (>= 3.19.92) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
root@ubuntu:/# apt-get install gnome-settings-daemon
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
gnome-settings-daemon : Depends: libpulse-mainloop-glib0 (>= 2.0) but it is not going to be installed
Recommends: pulseaudio
E: Unable to correct problems, you have held broken packages.
root@ubuntu:/# apt-get install libpulse-mainloop-glib0
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
libpulse-mainloop-glib0 : Depends: libpulse0 (= 1:13.99.1-1ubuntu3.8) but 1:13.99.1-1ubuntu3.13 is to be installed
E: Unable to correct problems, you have held broken packages.
更新 1
root@ubuntu:/# apt policy ubuntu-desktop
ubuntu-desktop:
Installed: (none)
Candidate: 1.450
Version table:
1.450 500
500 http://us.archive.ubuntu.com/ubuntu focal/main amd64 Packages
更新 2：
根据下面的评论，我添加了以下行/etc/apt/sources.list，这似乎解决了该问题：
deb http://archive.ubuntu.com/ubuntu/ focal-updates main restricted