Well, @downsideup, I was hoping your list file had an entry that was obviously corrupted, but either there’s an invisible character throwing it off or there’s something else wrong, and I’m invoking @Mattches for review and help if the following doesn’t work.
If your system updates everything else, could you double-check that your Ubuntu 18.04 is up to date, then try removing the list file, then repeating the creation of it and subsequent installation commands? If your system won’t update anything, then delete the list file first, then update your system, then repeat creation of list file and Brave installation commands.
You probably know how to do all of these, but just in case:
sudo apt-get update
sudo apt-get upgrade
sudo rm /etc/apt/sources.list.d/brave-browser-release.list
- To recreate list file and try to install Brave:
echo "deb [arch=amd64] https://brave-browser-apt-release.s3.brave.com/ stable main" | sudo tee /etc/apt/sources.list.d/brave-browser-release.list
sudo apt update
sudo apt install brave-browser