Docker installation on Linux Mint 19.2 doesn't work

sudo nano /etc/apt/sources.list.d/additional-repositories.list

add the following line in the file

deb [arch=amd64] https://download.docker.com/linux/ubuntu bionic stable

then,

sudo apt update

you know the rest of the steps. Good luck!

Leo's answer is very widely accepted but for some reason his solution doesn't work in my machine which is run by Linux Mint 19.3 Chinamon. So after doing some research I came out with this solution.

First Run this

echo -e "\ndeb [arch=amd64] https://download.docker.com/linux/ubuntu bionic stable" | sudo tee -a /etc/apt/sources.list

and then update the package index.

sudo apt-get update