"Unable to locate package" error in Ubuntu 18.04 on Windows 10

Question

I activated the Bash shell on Windows 10 (with the new update on Windows 10 which offers a Linux Bash shell).

The installation was a success, but I can't install anything...
When I ran, for example

sudo apt-get install cmatrix

it returned

Unable to locate package cmatrix

Can somebody help me with this?

Solution

First of all, try running sudo apt update. If that doesn't fix it, you might have an improperly configured /etc/apt/sources.list file.