Whenever trying to install some programs from source, or specifically running apt update, I recieve this message:E: The repository 'http://ftp.ca.debian.org/debian stretch/updates Release' does not have a Release file.N: Updating from such a repository can't be done securely, and is therefore disabled by default.N: See apt-secure(8) manpage for repository creation and user configuration details.I started getting this after adding the architecture i386. Without it, I would not be able to install the proprietary Nvidia driver, and Steam client would not start at all.This is what my /etc/apt/sources.list reads:deb http://ftp.ca.debian.org/debian/ stretch main contrib non-freedeb-src http://ftp.ca.debian.org/debian/ stretch main contrib non-freedeb http://ftp.ca.debian.org/debian/ stretch/updates main contrib non-freedeb-src http://ftp.ca.debian.org/debian/ stretch/updates main contrib non-free####stretch-updates, previously known as 'volatile'deb http://ftp.ca.debian.org/debian/ stretch-updates main contrib non-freedeb-src http://ftp.ca.debian.org/debian/ stretch-updates main contrib non-free
Debian: The repository does not have a Release file
debian;apt;package management
Youve got both stretch-updates and stretch/updates, but the latter doesnt exist any more (at least on the mirror youre using). You should remove the references to stretch/updates, or  if youre expecting the stretch/updates lines to provide security updates  replace them withdeb http://security.debian.org/ stretch/updates main contrib non-free