Update Package Lists
The CircleCI convenience images (based on Ubuntu) for the Docker executor often come with apt package lists left over from the image build process.
Over time these package lists become outdated and may contain urls that have since become invalid - in this case you will receive an error message along these lines:
E: Failed to fetch http://...../package.deb 404 Not Found
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?
To resolve this, the package lists need to be updated by running the following command before installing any packages:
sudo apt-get update