所以有两个PPA在期间引起GPG警告sudo apt update

W: GPG error: https://brave-browser-apt-release.s3.brave.com bionic InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 4FE13824E3FFC656
E: The repository 'https://brave-browser-apt-release.s3.brave.com bionic InRelease' is not signed.
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.
W: GPG error: http://repository.spotify.com stable InRelease: The following signatures couldn't be verified because the public key is not available: …

-- 我们的情况 --

过去几周，我们无法在 Ubuntu 16.04 LTS 系统上运行 do-release-upgrade。

我们有 100 多台机器需要升级。已阅读其他解决方案，但到目前为止它们都不起作用（例如：如何升级到较新版本的 Ubuntu？ 如何在 Ubuntu 上通过 do-release-upgrade 进行版本升级失败后删除过时的软件包？ 如何仅执行 LTS 升级？） - 除了手动更改 /etc/apt/sources.list[.d/]* 中的发行版的“暴力”方法之外。我不喜欢这种方法，因为它看起来过于混乱并且不是特别友好。

do-release-upgrade 在 16.04LTS 上是否损坏？do-release-upgrade 去年中期的某个时候有效，但现在不行了..

-- 一些信息.. --

* Require a command line based solution as we need to automate this.
  We will be updating over 100 machines
* None of the existing solutions get do-release-upgrade to work.
    sudo do-release-upgrade
    sudo do-release-upgrade -d
    sudo do-release-upgrade -c
* update-manager-core package is installed
* File …

我在哪里可以找到 16.04.1 的好的 sources.list？我搞砸了，不做备份。请告诉我在哪里可以找到好的？

（我刚刚从 ubuntu 18.04 迁移到 Ubuntu 20.04。）

我不明白什么

• 下面解释了我如何解决问题的过程和细节，但我真的不明白它说的部分

php7.4-mysql : Depends: php7.4-common (= 7.4.3-4ubuntu2.2) but 7.4.9-1+ubuntu18.04.1+deb.sury.org+1 is to be installed
E: Unable to correct problems, you have held broken packages.

• 我可以理解该软件包php7.4-mysql依赖on php7.4-common（已安装，所以我没有看到那里的问题），但它也说(= 7.4.3-4ubuntu2.2)然后我迷路了...... 7.4.3-4ubuntu2.2？那是什么？如果这还不够复杂，它会添加......but 7.4.9-1+ubuntu18.04.1+deb.sury.org+1然后我就是不知道如何克服这个问题。

更多见解

• 我知道有人问过类似的问题，我已经阅读过它们，并且发布的解决方案似乎无法解决我的问题。我正在尝试$ php artisan migrate在自己的生产环境中使用该命令（我雇用了一个托管服务器，我只是在摆弄它），然后我得到了输出......

 Illuminate\Database\QueryException 

  could not find driver (SQL: select * from information_schema.tables where table_schema = gastigram and table_name = migrations and table_type = 'BASE TABLE')

  at vendor/laravel/framework/src/Illuminate/Database/Connection.php:671
    667| …

我使用的是从 Oracle 网站下载的 .deb 包，而且我之前已经正确安装了它。但现在系统实际上没有任何变化，但它会抛出以下错误。我还可以在菜单中看到它的图标，但它没有打开。使用 Ubuntu 20.04.1 可能出现什么问题？

$ sudo dpkg -i Software/virtualbox-6.1_6.1.14-140239~Ubuntu~eoan_amd64.deb
Selecting previously unselected package virtualbox-6.1. 
(Reading database ... 240840 files and directories currently installed.)
Preparing to unpack virtualbox-6.1_6.1.14-140239~Ubuntu~eoan_amd64.deb ... 
Unpacking virtualbox-6.1 (6.1.14-140239~Ubuntu~eoan) ... 

dpkg: dependency problems prevent configuration of virtualbox-6.1: 
virtualbox-6.1 depends on libqt5opengl5 (= 5.0.2); however:  
Package libqt5opengl5 is not installed.  
virtualbox-6.1 depends on libqt5printsupport5 (=5.0.2); however:   
Package libqt5printsupport5 is not installed.  
virtualbox-6.1 depends on libsdl1.2debian (= 1.2.11); however:  
Package libsdl1.2debian is not installed.  
virtualbox-6.1 depends …

请问有人可以在这里发布 Hirsute Hippo 的sources.list 吗？

我知道这取决于互联网连接（WLAN 或电缆？）。

这可能会有所不同。

我对数据连接的差异感兴趣。

当我尝试更新运行 Ubuntu 18.04.1 LTS 的笔记本电脑时，我使用这些命令sudo apt update，sudo apt-get update并且每次收到此消息时：

E: The repository 'cdrom://Ubuntu 18.04 LTS _Bionic Beaver_ - Release amd64 (20180426) bionic 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.
W: GPG error: https://dl.bintray.com/resin-io/debian stable Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY …

我试图编辑 source.listapt-get install update并从中生成新的源代码repogen.simplylinux.ch，我不知道在编辑过程中发生了什么，但现在当我输入时，version它说：

WARNING:root:could not open file '/etc/apt/sources.list'
   version: command not found

当我这样做时，apt-get install mtools它说：

root@spider-laptop:~# apt-get install mtools
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Package mtools is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source  
E: Package 'mtools' has no installation candidate

我使用 Ubuntu 16.04。APT 似乎找不到包m4：

root@kevin:/# sudo apt install m4

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Package m4 is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

E: Package 'm4' has no installation candidate

我跑了：

sudo apt-get upgrade && apt-get update

这没有任何区别。

root@kevin:/# grep main /etc/apt/sources.list
# deb cdrom:[Ubuntu 16.04.3 LTS _Xenial Xerus_ - Release …

这个问题不是骗人的。我在这里收到了我想要的答案：https : //unix.stackexchange.com/a/411530/3285

以前，当我只是尝试更新时会收到此错误。我相信这个问题与VLC PPA有关，它在 Ubuntu 上一直是彻头彻尾的垃圾。rm为了清除*vlc*包，我实际上必须删除受包控制的文件。现在，我删除了那个文件，我可以相对轻松地删除 vlc 包。我想这会让我回到开始，我可以再次尝试安装，但是当我这样做时，我收到了这个错误，

sudo apt-get install vlc
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 …