Ubunutu 18.04 Updates 404 error

I run into this issue almost every time I set up a new box.

Run sudo apt update before you install the packages.

Set your system time to the correct time of your time zone and then try sudo apt update before running your command sudo apt-get install g++

If running from docker and you already have apt-get update in your Dockerfile try running with --no-cache or use cache busting.