deb-src http://archive.debian.org/debian/ jessie main deb http://security.debian.org jessie/updates main deb-src http://security.debian.org jessie/updates main deb http://ftp.de.debian.org/debian testing main $ apt-get update -qq W: GPG error: http://archive.debian.org/debian jessie Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 8B48AD6246925553 NO_PUBKEY 7638D0442B90D010 NO_PUBKEY CBF8D6FD518E17E1 E: The repository 'http://archive.debian.org/debian jessie Release' is not signed. Cleaning up project directory and file based variables ERROR: Job failed: exit code 1