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J'ai ceci maintenant, pourtant à ma connaissance je n'ai rien fait de spécial ces derniers jours, rien installé...

Target Packages (main/binary-amd64/Packages) is configured multiple times in /etc/apt/sources.list:5 and /etc/apt/sources.list.d/additional-repositories.list:2
Target Packages (main/binary-i386/Packages) is configured multiple times in /etc/apt/sources.list:5 and /etc/apt/sources.list.d/additional-repositories.list:2
Target Packages (main/binary-all/Packages) is configured multiple times in /etc/apt/sources.list:5 and /etc/apt/sources.list.d/additional-repositories.list:2
Target Translations (main/i18n/Translation-en_US) is configured multiple times in /etc/apt/sources.list:5 and /etc/apt/sources.list.d/additional-repositories.list:2
Target Translations (main/i18n/Translation-en) is configured multiple times in /etc/apt/sources.list:5 and /etc/apt/sources.list.d/additional-repositories.list:2
Target Packages (main/binary-amd64/Packages) is configured multiple times in /etc/apt/sources.list.d/signal-xenial.list:1 and /etc/apt/sources.list.d/signal-xenial.list:2
Target Packages (main/binary-all/Packages) is configured multiple times in /etc/apt/sources.list.d/signal-xenial.list:1 and /etc/apt/sources.list.d/signal-xenial.list:2
Target Translations (main/i18n/Translation-en_US) is configured multiple times in /etc/apt/sources.list.d/signal-xenial.list:1 and /etc/apt/sources.list.d/signal-xenial.list:2
Target Translations (main/i18n/Translation-en) is configured multiple times in /etc/apt/sources.list.d/signal-xenial.list:1 and /etc/apt/sources.list.d/signal-xenial.list:2
GPG error: https://dl.winehq.org/wine-builds/ubuntu xenial InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 76F1A20FF987672FThe repository 'https://dl.winehq.org/wine-builds/ubuntu xenial InRelease' is not signed.
Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
See apt-secure(8) manpage for repository creation and user configuration details.
The repository 'http://apt.mopidy.com stable Release' does not have a Release file.
Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
See apt-secure(8) manpage for repository creation and user configuration details.
GPG error: http://ftp.fau.de/mint/packages sylvia Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY A6616109451BBBF2
The repository 'http://ftp.fau.de/mint/packages sylvia Release' is not signed.
Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
See apt-secure(8) manpage for repository creation and user configuration details.
The repository 'http://ppa.launchpad.net/jonathonf/python-3.6/ubuntu xenial Release' does not have a Release file.
Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
See apt-secure(8) manpage for repository creation and user configuration details.
Failed to fetch http://apt.mopidy.com/dists/stable/main/binary-amd64/Packages 404 Not Found [IP: 185.199.108.153 80]Failed to fetch http://ppa.launchpad.net/jonathonf/python-3.6/ubuntu/dists/xenial/main/source/Sources 403 Forbidden [IP: 91.189.95.83 80]
Some index files failed to download. They have been ignored, or old ones used instead.

arnauld