Ubuntu 拒绝启动后，我不得不删除新内核版本。从那时起，更新管理器就一直无法工作，并且我收到以下错误。如何让更新管理器再次工作？
W: The repository 'http://ppa.launchpad.net/kernel-ppa/ppa/ubuntu xenial Release' does not have a Release file.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
W: The repository 'http://ppa.launchpad.net/tiheum/equinox/ubuntu xenial Release' does not have a Release file.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
W: http://archive.canonical.com/ubuntu/dists/precise/Release.gpg: Signature by key 630239CC130E1A7FD81A27B140976EAF437D05B5 uses weak digest algorithm (SHA1)
E: Failed to fetch http://ppa.launchpad.net/kernel-ppa/ppa/ubuntu/dists/xenial/main/binary-i386/Packages 404 Not Found
E: Failed to fetch http://ppa.launchpad.net/tiheum/equinox/ubuntu/dists/xenial/main/binary-i386/Packages 404 Not Found
E: W: Some index files failed to download. They have been ignored, or old ones used instead.
答案1
您正在尝试获取 xenial Ubuntu 发行版（16.04）的存储库内容，但是如果您转到http://ppa.launchpad.net/kernel-ppa/ppa/ubuntu/dists/您可以看到 xenial 不适用于此 ppa/。您的系统最近是否升级到 16.04？
它与删除内核没有任何共同之处。