当我更新和升级时，出现以下错误。
W: The repository 'http://ppa.launchpad.net/fossfreedom/packagefixes/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/thefanclub/grive-tools/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: GPG error: http://ppa.launchpad.net/boomaga/ppa/ubuntu xenial InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY A02ACCC9C6DAEA80
W: The repository 'http://ppa.launchpad.net/boomaga/ppa/ubuntu xenial InRelease' is not signed.
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/ubuntu-audio-dev/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: GPG error: http://ppa.launchpad.net/me-davidsansome/clementine-dev/ubuntu xenial InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 4F172854044A3B98
W: The repository 'http://ppa.launchpad.net/me-davidsansome/clementine-dev/ubuntu xenial InRelease' is not signed.
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.
E: Failed to fetch http://ppa.launchpad.net/fossfreedom/packagefixes/ubuntu/dists/xenial/main/binary-amd64/Packages 404 Not Found
E: Failed to fetch http://ppa.launchpad.net/thefanclub/grive-tools/ubuntu/dists/xenial/main/binary-amd64/Packages 404 Not Found
E: Failed to fetch http://ppa.launchpad.net/ubuntu-audio-dev/ppa/ubuntu/dists/xenial/main/source/Sources 404 Not Found
E: Some index files failed to download. They have been ignored, or old ones used instead.
我也检查了源列表。看起来一切都很好。但我仍然收到错误。
答案1
您需要进入System Settings-> Software & Updates。然后选择Ubuntu Software选项卡并取消选中这些项目；
http://ppa.launchpad.net/fossfreedom/packagefixes/ubuntu xenial Release
http://ppa.launchpad.net/thefanclub/grive-tools/ubuntu xenial Release
http://ppa.launchpad.net/boomaga/ppa/ubuntu xenial InRelease
http://ppa.launchpad.net/ubuntu-audio-dev/ppa/ubuntu xenial Release
http://ppa.launchpad.net/me-davidsansome/clementine-dev/ubuntu xenial InRelease
取消选中这些项目后，运行sudo apt update，您就可以继续更新系统。