我在终端中运行了这个命令：
sudo apt-get update
更新以以下错误报告结束：
W: A error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://extras.ubuntu.com precise Release: The following signatures were invalid: BADSIG 16126D3A3E5C1192 Ubuntu Extras Archive Automatic Signing Key <ftpmaster@ubuntu.com>
W: GPG error: http://ppa.launchpad.net precise Release: The following signatures were invalid: BADSIG 4C1CBC1B69B0E2F4 Launchpad PPA for Jonathan French
W: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/precise/Release
这是什么意思，为什么会这样？
这是问题 952287：[用户反馈 - 稳定] 由于 GPG 签名密钥过期，Linux 版 Chrome 无法安装/更新的报告
今天，apt在我所有的机器上运行时，谷歌 PPA 都会出现这个错误（对于google-chrome）：
me@mymachine:~$ sudo apt clean && sudo apt update && sudo apt full-upgrade -y && sudo apt autoremove -y && sudo apt autoclean -y && sudo snap refresh
[sudo] password for me:
Ign:1 http://dl.google.com/linux/chrome/deb stable InRelease
Hit:2 http://ppa.launchpad.net/graphics-drivers/ppa/ubuntu bionic InRelease
Hit:3 http://dl.google.com/linux/chrome/deb stable Release
Hit:4 http://archive.ubuntu.com/ubuntu bionic InRelease
Get:5 http://archive.ubuntu.com/ubuntu bionic-updates InRelease [88,7 kB]
Get:6 http://archive.ubuntu.com/ubuntu bionic-backports InRelease [74,6 kB]
Err:7 http://dl.google.com/linux/chrome/deb stable …今天我做了sudo apt upgrade，然后仔细检查了一下，做了sudo apt update。后者以：
Hit:5 http://dl.google.com/linux/chrome/deb stable InRelease
Get:6 https://repo.skype.com/deb stable InRelease [4,502 B]
Err:6 https://repo.skype.com/deb stable InRelease
The following signatures were invalid: EXPKEYSIG 1F3045A5DF7587C3 Skype Linux Client Repository <se-um@microsoft.com>
Fetched 4,502 B in 5s (894 B/s)
Reading package lists... Done
Building dependency tree
Reading state information... Done
All packages are up to date.
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. …我有一台 HP EliteBook 2540p。我想将 Ubuntu 16.04 升级到更新版本。我发现我需要升级到18.04才能升级到20.04。
我通过使用以下命令更新系统并升级软件和软件包来尝试推荐的过程：
sudo apt update && sudo apt upgrade
Hit:1 http://archive.canonical.com/ubuntu xenial InRelease
Hit:2 http://ppa.launchpad.net/canonical-chromium-builds/stage/ubuntu xenial InRelease
Hit:3 http://repo.mysql.com/apt/ubuntu xenial InRelease
Hit:4 http://packages.microsoft.com/repos/code stable InRelease
Ign:5 http://repo.vivaldi.com/stable/deb stable InRelease
Hit:6 http://dl.google.com/linux/chrome/deb stable InRelease
Hit:7 http://ma.archive.ubuntu.com/ubuntu xenial InRelease
Get:8 http://security.ubuntu.com/ubuntu xenial-security InRelease [109 kB]
Hit:9 http://ppa.launchpad.net/clipgrab-team/ppa/ubuntu xenial InRelease
Hit:10 http://repo.vivaldi.com/stable/deb stable Release
Get:11 http://ma.archive.ubuntu.com/ubuntu xenial-updates InRelease [109 kB]
Get:12 https://download.docker.com/linux/ubuntu xenial InRelease [66.2 kB]
Hit:13 http://ppa.launchpad.net/nathan-renniewaldock/flux/ubuntu xenial InRelease
Hit:14 https://deb.opera.com/opera-stable stable InRelease
Hit:15 https://brave-browser-apt-release.s3.brave.com xenial …