La mise à jour de 14.04 à 16.04 a échoué avec une erreur GPG

apt-get update after upgrade – Je reçois le message suivant

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://ua.archive.ubuntu.com/ubuntu xenial InRelease: At least one invalid signature was encountered. W: The repository 'http://ua.archive.ubuntu.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://ua.archive.ubuntu.com/ubuntu xenial-security InRelease: At least one invalid signature was encountered. W: The repository 'http://ua.archive.ubuntu.com/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://ua.archive.ubuntu.com/ubuntu xenial-updates InRelease: At least one invalid signature was encountered. W: The repository 'http://ua.archive.ubuntu.com/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://ua.archive.ubuntu.com/ubuntu xenial-proposed InRelease: At least one invalid signature was encountered. W: The repository 'http://ua.archive.ubuntu.com/ubuntu xenial-proposed 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://ua.archive.ubuntu.com/ubuntu xenial-backports InRelease: At least one invalid signature was encountered. W: The repository 'http://ua.archive.ubuntu.com/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. 

A tenté

 sudo apt-get clean sudo mv /var/lib/apt/lists /tmp sudo mkdir -p /var/lib/apt/lists/partial sudo apt-get clean sudo apt-get update 

Cela n’a pas aidé.

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 ###### Ubuntu Main Repos deb http://ua.archive.ubuntu.com/ubuntu/ xenial main ressortingcted universe multiverse ###### Ubuntu Update Repos deb http://ua.archive.ubuntu.com/ubuntu/ xenial-security main ressortingcted universe multiverse deb http://ua.archive.ubuntu.com/ubuntu/ xenial-updates main ressortingcted universe multiverse deb http://ua.archive.ubuntu.com/ubuntu/ xenial-proposed main ressortingcted universe multiverse deb http://ua.archive.ubuntu.com/ubuntu/ xenial-backports main ressortingcted universe multiverse ###### Ubuntu Partner Repo deb http://archive.canonical.com/ubuntu xenial partner 

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