When I do sudo apt-get update I get the following error:
Err:23 https://download.docker.com/linux/ubuntu serena/stable amd64 Packages 404 Not Found
E: Failed to fetch https://download.docker.com/linux/ubuntu/dists/serena/stable/binary-amd64/Packages 404 Not Found
E: Some index files failed to download. They have been ignored, or old ones used instead.
I know there is a similar question here
but still I am not able to solve the problem. I am running on
Distributor ID: LinuxMint
Description: Linux Mint 18.1 Serena
Release: 18.1
and the file /etc/apt/sources.list which seems to be important contains the line
#deb cdrom:[Linux Mint 18.1 _Serena_ - Release amd64 20161213]/ xenial contrib main non-free
Any help is very much appreciated.