有一天，我发现了如下错误消息，我不知道发生了什么，需要检查什么解决方案才能修复，我需要您的帮助。
.............
Err http://ppa.launchpad.net saucy/main amd64 Packages
404 Not Found
Err http://ppa.launchpad.net saucy/main i386 Packages
404 Not Found
Ign http://ppa.launchpad.net saucy/main Translation-en_US
Ign http://ppa.launchpad.net saucy/main Translation-en
Fetched 1,498 kB in 2min 56s (8,478 B/s)
Reading package lists... Done
W: GPG error: http://dl.google.com stable Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY A040830F7FAC5991
W: GPG error: http://dl.google.com stable Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY A040830F7FAC5991
W: GPG error: http://www.geogebra.net stable InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY C072A32983A736CF
W: GPG error: http://deb.torproject.org saucy InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 74A941BA219EC810
W: GPG error: http://archive.canonical.com saucy Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5 NO_PUBKEY 3B4FE6ACC0B21F32
W: GPG error: http://extras.ubuntu.com saucy Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 16126D3A3E5C1192
W: GPG error: http://archive.ubuntu.com saucy Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5 NO_PUBKEY 3B4FE6ACC0B21F32
W: GPG error: http://archive.ubuntu.com saucy-updates Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5 NO_PUBKEY 3B4FE6ACC0B21F32
W: GPG error: http://archive.ubuntu.com saucy-security Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5 NO_PUBKEY 3B4FE6ACC0B21F32
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://archive.ubuntu.com saucy-proposed Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5 NO_PUBKEY 3B4FE6ACC0B21F32
W: GPG error: https://private-ppa.launchpad.net saucy Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY E131728675254D99
W: GPG error: https://private-ppa.launchpad.net saucy Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY E131728675254D99
W: GPG error: https://private-ppa.launchpad.net saucy Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY E131728675254D99
W: GPG error: https://private-ppa.launchpad.net saucy Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY E131728675254D99
W: GPG error: https://private-ppa.launchpad.net saucy Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY E131728675254D99
W: GPG error: https://private-ppa.launchpad.net saucy Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY E131728675254D99
W: GPG error: https://private-ppa.launchpad.net saucy Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY E131728675254D99
W: GPG error: https://private-ppa.launchpad.net saucy Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY E131728675254D99
W: GPG error: https://private-ppa.launchpad.net saucy Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY E131728675254D99
W: GPG error: http://ppa.launchpad.net saucy Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 8FC2C0DC77296259
W: Failed to fetch https://ppa.launchpad.net/clamtk/dists/saucy/main/binary-amd64/Packages
W: Failed to fetch https://ppa.launchpad.net/clamtk/dists/saucy/main/binary-i386/Packages
W: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/saucy-proposed/Release
W: Failed to fetch http://ppa.launchpad.net/birdie-team/stable/ubuntu/dists/saucy/main/binary-amd64/Packages 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/birdie-team/stable/ubuntu/dists/saucy/main/binary-i386/Packages 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/clicompanion-devs/clicompanion-nightlies/ubuntu/dists/saucy/main/binary-amd64/Packages 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/clicompanion-devs/clicompanion-nightlies/ubuntu/dists/saucy/main/binary-i386/Packages 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/openshot.developers/ppa/ubuntu/dists/saucy/main/binary-amd64/Packages 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/openshot.developers/ppa/ubuntu/dists/saucy/main/binary-i386/Packages 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/ubuntu-vn/ppa/ubuntu/dists/saucy/main/binary-amd64/Packages 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/ubuntu-vn/ppa/ubuntu/dists/saucy/main/binary-i386/Packages 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/ylatuya/ppa/ubuntu/dists/saucy/main/binary-amd64/Packages 404 Not Found
W: Failed to fetch http://ppa.launchpad.net/ylatuya/ppa/ubuntu/dists/saucy/main/binary-i386/Packages 404 Not Found
W: Some index files failed to download. They have been ignored, or old ones used instead.
此外，还会定期出现如下消息：
按照以下部分“如何消除这些错误”，修复了一些 PPA，但不是全部，然后按照 Danilo 在同一页面中的说明禁用所有 PPA：
最终，我意识到我的错误实例是“无法验证以下签名，因为公钥不可用：NO_PUBKEY......”
Ign http://archive.ubuntu.com saucy-proposed/universe Translation-en_US
Fetched 27.6 MB in 1min 36s (287 kB/s)
Reading package lists... Done
W: GPG error: http://archive.ubuntu.com saucy Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5 NO_PUBKEY 3B4FE6ACC0B21F32
W: GPG error: http://archive.ubuntu.com saucy-updates Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5 NO_PUBKEY 3B4FE6ACC0B21F32
W: GPG error: http://archive.ubuntu.com saucy-security Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5 NO_PUBKEY 3B4FE6ACC0B21F32
W: GPG error: http://archive.ubuntu.com saucy-proposed Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 40976EAF437D05B5 NO_PUBKEY 3B4FE6ACC0B21F32
我该如何解决这个问题？
:~$ cat /etc/apt/sources.list
# deb cdrom:[Ubuntu 13.10 _Saucy Salamander_ - Release amd64 (20131016.1)]/ saucy main restricted
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://archive.ubuntu.com/ubuntu saucy main restricted
deb-src http://archive.ubuntu.com/ubuntu saucy main restricted
## Major bug fix updates produced after the final release of the
## distribution.
deb http://archive.ubuntu.com/ubuntu saucy-updates main restricted
deb-src http://archive.ubuntu.com/ubuntu saucy-updates main restricted
## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
deb http://archive.ubuntu.com/ubuntu saucy universe
deb-src http://archive.ubuntu.com/ubuntu saucy universe
deb http://archive.ubuntu.com/ubuntu saucy-updates universe
deb-src http://archive.ubuntu.com/ubuntu saucy-updates universe
## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team, and may not be under a free licence. Please satisfy yourself as to
## your rights to use the software. Also, please note that software in
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
deb http://archive.ubuntu.com/ubuntu saucy multiverse
deb-src http://archive.ubuntu.com/ubuntu saucy multiverse
deb http://archive.ubuntu.com/ubuntu saucy-updates multiverse
deb-src http://archive.ubuntu.com/ubuntu saucy-updates multiverse
## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
deb http://archive.ubuntu.com/ubuntu saucy-security main restricted
deb-src http://archive.ubuntu.com/ubuntu saucy-security main restricted
deb http://archive.ubuntu.com/ubuntu saucy-security universe
deb-src http://archive.ubuntu.com/ubuntu saucy-security universe
deb http://archive.ubuntu.com/ubuntu saucy-security multiverse
deb-src http://archive.ubuntu.com/ubuntu saucy-security multiverse
## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu, but is offered by Canonical and the
## respective vendors as a service to Ubuntu users.
deb http://archive.canonical.com/ubuntu saucy partner
deb-src http://archive.canonical.com/ubuntu saucy partner
## This software is not part of Ubuntu, but is offered by third-party
## developers who want to ship their latest software.
deb http://extras.ubuntu.com/ubuntu saucy main
deb-src http://extras.ubuntu.com/ubuntu saucy main
# deb https://ppa.launchpad.net/clamtk saucy main
# deb-src https://ppa.launchpad.net/clamtk saucy main
deb http://deb.torproject.org/torproject.org saucy main
deb http://archive.ubuntu.com/ubuntu saucy-proposed universe main restricted multiverse
和:~$ cat /etc/apt/sources.list.d/*.list
deb http://ppa.launchpad.net/apt-fast/stable/ubuntu saucy main
deb-src http://ppa.launchpad.net/apt-fast/stable/ubuntu saucy main
deb http://ppa.launchpad.net/atareao/atareao/ubuntu saucy main
deb-src http://ppa.launchpad.net/atareao/atareao/ubuntu saucy main
# deb http://ppa.launchpad.net/birdie-team/stable/ubuntu saucy main
# deb-src http://ppa.launchpad.net/birdie-team/stable/ubuntu saucy main
deb http://ppa.launchpad.net/cairo-dock-team/ppa/ubuntu saucy main
deb-src http://ppa.launchpad.net/cairo-dock-team/ppa/ubuntu saucy main
deb http://ppa.launchpad.net/ehoover/compholio/ubuntu saucy main
deb-src http://ppa.launchpad.net/ehoover/compholio/ubuntu saucy main
deb http://ppa.launchpad.net/ffdiaporamateam/stable/ubuntu saucy main
deb-src http://ppa.launchpad.net/ffdiaporamateam/stable/ubuntu saucy main
deb http://ppa.launchpad.net/fossfreedom/packagefixes/ubuntu saucy main
deb-src http://ppa.launchpad.net/fossfreedom/packagefixes/ubuntu saucy main
deb http://ppa.launchpad.net/fossfreedom/rhythmbox-plugins/ubuntu saucy main
deb-src http://ppa.launchpad.net/fossfreedom/rhythmbox-plugins/ubuntu saucy main
deb http://ppa.launchpad.net/fossfreedom/rhythmbox/ubuntu saucy main
deb-src http://ppa.launchpad.net/fossfreedom/rhythmbox/ubuntu saucy main
deb http://ppa.launchpad.net/gabriel1984sibiu/aplicatii/ubuntu saucy main
# deb-src http://ppa.launchpad.net/gabriel1984sibiu/aplicatii/ubuntu saucy main
### THIS FILE IS AUTOMATICALLY CONFIGURED ###
# You may comment out this entry, but any other modifications may be lost.
deb http://www.geogebra.net/linux/ stable main
deb http://dl.google.com/linux/chrome/deb/ stable main
### THIS FILE IS AUTOMATICALLY CONFIGURED ###
# You may comment out this entry, but any other modifications may be lost.
#deb http://dl.google.com/linux/talkplugin/deb/ stable main
deb http://ppa.launchpad.net/gstreamer-developers/ppa/ubuntu saucy main
deb-src http://ppa.launchpad.net/gstreamer-developers/ppa/ubuntu saucy main
deb http://ppa.launchpad.net/jacob/media/ubuntu saucy main
deb-src http://ppa.launchpad.net/jacob/media/ubuntu saucy main
# deb http://ppa.launchpad.net/landronimirc/clamtk/ubuntu saucy main
# deb-src http://ppa.launchpad.net/landronimirc/clamtk/ubuntu saucy main
deb http://ppa.launchpad.net/libreoffice/ppa/ubuntu saucy main
deb-src http://ppa.launchpad.net/libreoffice/ppa/ubuntu saucy main
deb http://ppa.launchpad.net/linrunner/tlp/ubuntu saucy main
deb http://ppa.launchpad.net/me-davidsansome/clementine/ubuntu saucy main
deb-src http://ppa.launchpad.net/me-davidsansome/clementine/ubuntu saucy main
## Please report any bug on https://bugs.launchpad.net/medibuntu/
deb http://ppa.launchpad.net/mqchael/pipelight/ubuntu saucy main
deb-src http://ppa.launchpad.net/mqchael/pipelight/ubuntu saucy main
deb http://ppa.launchpad.net/nathan-renniewaldock/xbmc-stable/ubuntu saucy main
deb-src http://ppa.launchpad.net/nathan-renniewaldock/xbmc-stable/ubuntu saucy main
deb http://ppa.launchpad.net/nilarimogard/webupd8/ubuntu saucy main
deb-src http://ppa.launchpad.net/nilarimogard/webupd8/ubuntu saucy main
# deb http://ppa.launchpad.net/no1wantdthisname/openjdk-fontfix/ubuntu saucy main
# deb-src http://ppa.launchpad.net/no1wantdthisname/openjdk-fontfix/ubuntu saucy main
deb http://ppa.launchpad.net/noobslab/pear-apps/ubuntu saucy main
deb-src http://ppa.launchpad.net/noobslab/pear-apps/ubuntu saucy main
deb http://ppa.launchpad.net/nuvola-player-builders/stable/ubuntu saucy main
deb-src http://ppa.launchpad.net/nuvola-player-builders/stable/ubuntu saucy main
deb http://ppa.launchpad.net/nvbn-rm/ppa/ubuntu saucy main
deb-src http://ppa.launchpad.net/nvbn-rm/ppa/ubuntu saucy main
# This file makes sure that Opera Browser is kept up-to-date
# as part of regular system upgrades
# The line above will make sure you get all final public releases.
# Uncomment the following line if you want to get alpha and beta
# releases, too.
deb http://ppa.launchpad.net/peterlevi/ppa/ubuntu saucy main
deb-src http://ppa.launchpad.net/peterlevi/ppa/ubuntu saucy main
deb https://private-ppa.launchpad.net/commercial-ppa-uploaders/able2extract/ubuntu saucy main #Added by software-center; credentials stored in /etc/apt/auth.conf
deb https://private-ppa.launchpad.net/commercial-ppa-uploaders/chess/ubuntu saucy main #Added by software-center; credentials stored in /etc/apt/auth.conf
deb https://private-ppa.launchpad.net/commercial-ppa-uploaders/color-by-numbers-halloween-free/ubuntu saucy main #Added by software-center; credentials stored in /etc/apt/auth.conf
deb https://private-ppa.launchpad.net/commercial-ppa-uploaders/master-pdf-editor/ubuntu saucy main #Added by software-center; credentials stored in /etc/apt/auth.conf
deb https://private-ppa.launchpad.net/commercial-ppa-uploaders/minitube-ubuntu/ubuntu saucy main #Added by software-center; credentials stored in /etc/apt/auth.conf
deb https://private-ppa.launchpad.net/commercial-ppa-uploaders/outreel/ubuntu saucy main #Added by software-center; credentials stored in /etc/apt/auth.conf
deb https://private-ppa.launchpad.net/commercial-ppa-uploaders/splashtop-client/ubuntu saucy main #Added by software-center; credentials stored in /etc/apt/auth.conf
deb https://private-ppa.launchpad.net/commercial-ppa-uploaders/varicad-viewer/ubuntu saucy main #Added by software-center; credentials stored in /etc/apt/auth.conf
deb https://private-ppa.launchpad.net/commercial-ppa-uploaders/wuala/ubuntu saucy main #Added by software-center; credentials stored in /etc/apt/auth.conf
deb http://ppa.launchpad.net/rvm/smplayer/ubuntu saucy main
deb-src http://ppa.launchpad.net/rvm/smplayer/ubuntu saucy main
deb http://ppa.launchpad.net/saiarcot895/myppa/ubuntu saucy main
deb-src http://ppa.launchpad.net/saiarcot895/myppa/ubuntu saucy main
deb http://ppa.launchpad.net/skunk/pepper-flash/ubuntu saucy main
deb-src http://ppa.launchpad.net/skunk/pepper-flash/ubuntu saucy main
deb http://ppa.launchpad.net/skype-wrapper/ppa/ubuntu saucy main
deb-src http://ppa.launchpad.net/skype-wrapper/ppa/ubuntu saucy main
deb http://ppa.launchpad.net/tualatrix/ppa/ubuntu saucy main
deb-src http://ppa.launchpad.net/tualatrix/ppa/ubuntu saucy main
# deb http://ppa.launchpad.net/ubuntu-vn/ppa/ubuntu saucy main
# deb-src http://ppa.launchpad.net/ubuntu-vn/ppa/ubuntu saucy main
deb http://ppa.launchpad.net/videolan/stable-daily/ubuntu saucy main
deb http://ppa.launchpad.net/vincent-c/cherrytree/ubuntu saucy main
deb-src http://ppa.launchpad.net/vincent-c/cherrytree/ubuntu saucy main
deb http://ppa.launchpad.net/webupd8team/java/ubuntu saucy main
deb-src http://ppa.launchpad.net/webupd8team/java/ubuntu saucy main
deb-src http://ppa.launchpad.net/webupd8team/java/ubuntu saucy main
deb http://ppa.launchpad.net/webupd8team/tor-browser/ubuntu saucy main
deb-src http://ppa.launchpad.net/webupd8team/tor-browser/ubuntu saucy main
deb http://ppa.launchpad.net/webupd8team/y-ppa-manager/ubuntu saucy main
deb-src http://ppa.launchpad.net/webupd8team/y-ppa-manager/ubuntu saucy main
deb http://ppa.launchpad.net/wfg/0ad/ubuntu saucy main
deb-src http://ppa.launchpad.net/wfg/0ad/ubuntu saucy main
# deb http://ppa.launchpad.net/ylatuya/ppa/ubuntu saucy main
# deb-src http://ppa.launchpad.net/ylatuya/ppa/ubuntu saucy main
答案1
答案2
以下是经过测试的删除令人讨厌的 GPG 错误的分步方法：
删除以下目录下的所有关键文件：“/etc/apt/trusted.gpg.d”：
sudo rm /etc/apt/trusted.gpg.d/*安装 y-ppa-manager：
sudo add-apt-repository ppa:webupd8team/y-ppa-manager sudo apt-get update sudo apt-get install y-ppa-manager启动它：
gksudo y-ppa-manager向下滚动并选择“高级”
现在选择“尝试导入所有缺失的 GPG 密钥”并单击确定。
这可能需要一两分钟。完成后您会收到通知。
更新apt：
sudo apt-get update不再有 NO_PUBKEY 错误:)
ps：问题似乎与这漏洞。