Сегодня обнаружил, что внезапно в моей убунте сломались все прописаные репозитории. apt пишет вот что.
W: GPG error: http://ftp.byfly.by/ubuntu xenial InRelease: At least one invalid signature was encountered.
W: The repository 'http://ftp.byfly.by/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: GPG error: http://ftp.byfly.by/ubuntu xenial-updates InRelease: At least one invalid signature was encountered.
W: The repository 'http://ftp.byfly.by/ubuntu xenial-updates 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: GPG error: http://ftp.byfly.by/ubuntu xenial-backports InRelease: At least one invalid signature was encountered.
W: The repository 'http://ftp.byfly.by/ubuntu xenial-backports 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: GPG error: http://ftp.byfly.by/ubuntu xenial-security InRelease: At least one invalid signature was encountered.
W: The repository 'http://ftp.byfly.by/ubuntu xenial-security 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: GPG error: http://archive.canonical.com/ubuntu xenial InRelease: At least one invalid signature was encountered.
W: The repository 'http://archive.canonical.com/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: GPG error: http://dl.google.com/linux/chrome/deb stable Release: At least one invalid signature was encountered.
W: The repository 'http://dl.google.com/linux/chrome/deb stable Release' 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: GPG error: https://repo.skype.com/deb stable InRelease: At least one invalid signature was encountered.
W: The repository 'https://repo.skype.com/deb stable 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: GPG error: https://packagecloud.io/slacktechnologies/slack/debian jessie InRelease: At least one invalid signature was encountered.
W: The repository 'https://packagecloud.io/slacktechnologies/slack/debian jessie 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.
В интернете нашел советы очистить кеш таким образом
sudo apt-get clean
cd /var/lib/apt
sudo mv lists lists.old
sudo mkdir -p lists/partial
sudo apt-get clean
sudo apt-get update