Unable to locate package docker-engine

Solution 1:

Try 'uname -a' and make sure you're running a 64-bit architecture:

Docker requires a 64-bit installation regardless of your Ubuntu version.

https://docs.docker.com/engine/installation/linux/ubuntulinux/

Solution 2:

As mentioned in the comments, you have to

1. find out your distribution name via lsb_release -c
2. the file /etc/apt/sources.list.d/docker.list should have the following content (and nothing else): deb https://apt.dockerproject.org/repo ubuntu-VERSION-NAME main

In my case (Ubuntu 14.04 aka 'trusty') I added deb https://apt.dockerproject.org/repo ubuntu-trusty main

Solution 3:

I fixed this issue by running apt-get update followed by apt-get install docker.io