W: The repository 'https://apt.dockerproject.org/repo ubuntu-xenial 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://apt.dockerproject.org/repo/dists/ubuntu-xenial/main/binary-amd6…
E: Some index files failed to download. They have been ignored, or old ones used instead.