当我尝试使用更新时， apt-get update出现以下错误（当我按照此处的一些教程进行操作时，错误数量不断增加）。
W: GPG error: http://download.opensuse.org/repositories/home:/Horst3180/xUbuntu_16.04 Release: The following signatures were invalid: EXPKEYSIG 5A7D1D38BEB6D886 home:Horst3180 OBS Project <home:[email protected]>
E: The repository 'http://download.opensuse.org/repositories/home:/Horst3180/xUbuntu_16.04 Release' 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: Target Packages (Packages) is configured multiple times in /etc/apt/sources.list.d/arc-theme.list:1 and /etc/apt/sources.list.d/home:Horst3180.list:1
W: Target Translations (en_US) is configured multiple times in /etc/apt/sources.list.d/arc-theme.list:1 and /etc/apt/sources.list.d/home:Horst3180.list:1
W: Target Translations (en) is configured multiple times in /etc/apt/sources.list.d/arc-theme.list:1 and /etc/apt/sources.list.d/home:Horst3180.list:1
这解决方案给了我上面列表中的最后三个 W，并且我还尝试更新过期的签名（但没有成功）。
这是我跑步时得到的cat /etc/apt/sources.list。
# deb cdrom:[Ubuntu 18.04.3 LTS _Bionic Beaver_ - Release amd64 (20190805)]/ bionic main restricted
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://es.archive.ubuntu.com/ubuntu/ bionic main restricted
# deb-src http://es.archive.ubuntu.com/ubuntu/ bionic main restricted
## Major bug fix updates produced after the final release of the
## distribution.
deb http://es.archive.ubuntu.com/ubuntu/ bionic-updates main restricted
# deb-src http://es.archive.ubuntu.com/ubuntu/ bionic-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://es.archive.ubuntu.com/ubuntu/ bionic universe
# deb-src http://es.archive.ubuntu.com/ubuntu/ bionic universe
deb http://es.archive.ubuntu.com/ubuntu/ bionic-updates universe
# deb-src http://es.archive.ubuntu.com/ubuntu/ bionic-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://es.archive.ubuntu.com/ubuntu/ bionic multiverse
# deb-src http://es.archive.ubuntu.com/ubuntu/ bionic multiverse
deb http://es.archive.ubuntu.com/ubuntu/ bionic-updates multiverse
# deb-src http://es.archive.ubuntu.com/ubuntu/ bionic-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://es.archive.ubuntu.com/ubuntu/ bionic-backports main restricted universe multiverse
# deb-src http://es.archive.ubuntu.com/ubuntu/ bionic-backports main restricted universe 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 bionic partner
# deb-src http://archive.canonical.com/ubuntu bionic partner
deb http://security.ubuntu.com/ubuntu bionic-security main restricted
# deb-src http://security.ubuntu.com/ubuntu bionic-security main restricted
deb http://security.ubuntu.com/ubuntu bionic-security universe
# deb-src http://security.ubuntu.com/ubuntu bionic-security universe
deb http://security.ubuntu.com/ubuntu bionic-security multiverse
# deb-src http://security.ubuntu.com/ubuntu bionic-security multiverse
deb http://archive.canonical.com/ precise partner
# deb-src http://archive.canonical.com/ precise partner
我有以下文件/etc/apt/sources.list.d。
arc-theme.list home:Horst3180.list
arc-theme.list.save home:Horst3180.list.save
google-chrome.list sunderme-ubuntu-texstudio-bionic.list
google-chrome.list.save sunderme-ubuntu-texstudio-bionic.list.save