On a brand new server running Ubuntu 16.04.3, I follow the steps to install MongoDB Community Edition, as described here . After executing the line `sudo apt-get install mongodb-org`, I get this warning: WARNING: The following packages cannot be authenticated! mongodb-org-shell mongodb-org-server mongodb-org-mongos mongodb-org-tools mongodb-org Install these packages without verification? [y/N] I tried the steps proposed by Brian Samek for the earlier bug, updating them to the current version: sudo rm /etc/apt/sources.list.d/mongodb-org-3.6.list sudo apt-get update echo "deb [ arch=amd64,arm64 ] http://repo.mongodb.org/apt/ubuntu xenial/mongodb-org/testing multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-3.6.list sudo apt-get update sudo apt-get install -y mongodb-org My complete terminal session is shown below. $ sudo find / -name "mongo*" /etc/apt/sources.list.d/mongodb-org-3.6.list blackslate@lexogram:~$ sudo rm /etc/apt/sources.list.d/mongodb-org-3.6.list blackslate@lexogram:~$ sudo find / -name "mongo*" blackslate@lexogram:~$ sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv 2930ADAE8CAF5059EE73BB4B58712A2291FA4AD5 Executing: /tmp/tmp.17prbTsQbs/gpg.1.sh --keyserver hkp://keyserver.ubuntu.com:80 --recv 2930ADAE8CAF5059EE73BB4B58712A2291FA4AD5 gpg: requesting key 91FA4AD5 from hkp server keyserver.ubuntu.com gpg: key 91FA4AD5: "MongoDB 3.6 Release Signing Key <packaging@mongodb.com>" not changed gpg: Total number processed: 1 gpg: unchanged: 1 blackslate@lexogram:~$ echo "deb [ arch=amd64,arm64 ] http://repo.mongodb.org/apt/ubuntu xenial/mongodb-org/testing multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-3.6.list deb [ arch=amd64,arm64 ] http://repo.mongodb.org/apt/ubuntu xenial/mongodb-org/testing multiverse blackslate@lexogram:~$ blackslate@lexogram:~$ sudo apt-get update Get:1 http://security.ubuntu.com/ubuntu xenial-security InRelease [102 kB] Hit:2 http://mirrors.melbourne.co.uk/ubuntu xenial InRelease Hit:3 http://mirrors.melbourne.co.uk/ubuntu xenial-updates InRelease Hit:4 http://mirrors.melbourne.co.uk/ubuntu xenial-backports InRelease Ign:5 http://repo.mongodb.org/apt/ubuntu xenial/mongodb-org/testing InRelease Hit:6 http://repo.mongodb.org/apt/ubuntu xenial/mongodb-org/testing Release Get:7 http://repo.mongodb.org/apt/ubuntu xenial/mongodb-org/testing Release.gpg [801 B] Ign:7 http://repo.mongodb.org/apt/ubuntu xenial/mongodb-org/testing Release.gpg Fetched 103 kB in 0s (152 kB/s) Reading package lists... Done W: GPG error: http://repo.mongodb.org/apt/ubuntu xenial/mongodb-org/testing Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY BC711F9BA15703C6 *W: The repository 'http://repo.mongodb.org/apt/ubuntu xenial/mongodb-org/testing 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. blackslate@lexogram:~$ sudo apt-get install mongodb-org Reading package lists... Done Building dependency tree Reading state information... Done The following additional packages will be installed: mongodb-org-mongos mongodb-org-server mongodb-org-shell mongodb-org-tools The following NEW packages will be installed mongodb-org mongodb-org-mongos mongodb-org-server mongodb-org-shell mongodb-org-tools 0 to upgrade, 5 to newly install, 0 to remove and 0 not to upgrade. Need to get 68.8 MB of archives. After this operation, 282 MB of additional disk space will be used. Do you want to continue? [Y/n] Y *WARNING: The following packages cannot be authenticated! mongodb-org-shell mongodb-org-server mongodb-org-mongos mongodb-org-tools mongodb-org Install these packages without verification? [y/N] *