Как обновить Docker Ubuntu 16?

Question

[di]

Хочу обновить docker.
Делаю все по официальной доке: https://docs.docker.com/engine/install/ubuntu/

После

sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux ubuntu $(lsb_release -cs) stable"

делаю
sudo apt-get update

И получаю:

W: The repository 'https://download.docker.com/linux ubuntu Release' does not have a Release file.
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.
E: Failed to fetch https://download.docker.com/linux/dists/ubuntu/xenial/binary-amd64/Packages  404  Not Found
E: Some index files failed to download. They have been ignored, or old ones used instead.

что за wtf? как лечится?