我的 Linux Mint 20 安装突然停止更新。更新管理器显示“您的 APT 配置已损坏”。运行 apt update 会产生以下消息：
Get:1 http://security.ubuntu.com/ubuntu focal-security InRelease [114 kB]
Get:2 http://ppa.launchpad.net/kdenlive/kdenlive-stable/ubuntu focal InRelease [18,1 kB]
Get:3 http://archive.ubuntu.com/ubuntu focal InRelease [265 kB]
Err:2 http://ppa.launchpad.net/kdenlive/kdenlive-stable/ubuntu focal InRelease
At least one invalid signature was encountered.
Err:1 http://security.ubuntu.com/ubuntu focal-security InRelease
At least one invalid signature was encountered.
Err:3 http://archive.ubuntu.com/ubuntu focal InRelease
At least one invalid signature was encountered.
Get:4 http://archive.ubuntu.com/ubuntu focal-updates InRelease [114 kB]
Err:4 http://archive.ubuntu.com/ubuntu focal-updates InRelease
At least one invalid signature was encountered.
Get:5 http://archive.ubuntu.com/ubuntu focal-backports InRelease [108 kB]
Err:5 http://archive.ubuntu.com/ubuntu focal-backports InRelease
At least one invalid signature was encountered.
Ign:6 http://packages.linuxmint.com ulyana InRelease
Get:7 http://packages.linuxmint.com ulyana Release [24,1 kB]
Get:8 http://packages.linuxmint.com ulyana Release.gpg [833 B]
Ign:8 http://packages.linuxmint.com ulyana Release.gpg
Get:9 http://archive.canonical.com/ubuntu focal InRelease [12,1 kB]
Err:9 http://archive.canonical.com/ubuntu focal InRelease
At least one invalid signature was encountered.
Reading package lists... Done
W: GPG error: http://ppa.launchpad.net/kdenlive/kdenlive-stable/ubuntu focal InRelease: At least one invalid signature was encountered.
E: The repository 'http://ppa.launchpad.net/kdenlive/kdenlive-stable/ubuntu focal 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://security.ubuntu.com/ubuntu focal-security InRelease: At least one invalid signature was encountered.
E: The repository 'http://security.ubuntu.com/ubuntu focal-security 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://archive.ubuntu.com/ubuntu focal InRelease: At least one invalid signature was encountered.
E: The repository 'http://archive.ubuntu.com/ubuntu focal 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://archive.ubuntu.com/ubuntu focal-updates InRelease: At least one invalid signature was encountered.
E: The repository 'http://archive.ubuntu.com/ubuntu focal-updates 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://archive.ubuntu.com/ubuntu focal-backports InRelease: At least one invalid signature was encountered.
E: The repository 'http://archive.ubuntu.com/ubuntu focal-backports 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://packages.linuxmint.com ulyana Release: At least one invalid signature was encountered.
E: The repository 'http://packages.linuxmint.com ulyana 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: GPG error: http://archive.canonical.com/ubuntu focal InRelease: At least one invalid signature was encountered.
E: The repository 'http://archive.canonical.com/ubuntu focal 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.
我尝试运行 apt clean，但这并没有解决问题。此外，apt-key list 给出了以下奇怪的消息：
base64: invalid input
请帮忙。
答案1
找到了适合我的情况的解决方案！
apt-get update在许多存储库中写道“至少遇到一个无效签名”。没有关于丢失 GPG 密钥的消息。与您的输出完全一样，但其他存储库也是如此。
我跑步apt-key list并且在某处注意到了base64: invalid input一条消息。
这是我输出的中间部分
/etc/apt/trusted.gpg.d/nordvpn-keyring.gpg
------------------------------------------
pub rsa4096 2018-08-02 [SC]
BC54 80EF EC5C 081C E5BC FBE2 6B21 9E53 5C96 4CA1
uid [ unknown] NordVPN <[email protected]>
sub rsa4096 2018-08-02 [S]
base64: invalid input <--- THIS IS THE PROBLEM 答案2
如果apt-get update、 apt-get autoclean、sudo apt-get clean不起作用，并且您没有使用它，您可以尝试通过修改（使用 nano、vim 或其他）文件 来手动删除导致问题的源/etc/apt/sources.list。否则，您可以尝试使用 手动添加所需源的缺失/损坏的 GPG 密钥wget -qO - <link_to_source_key> | sudo apt-key add -