I have updated the
/etc/apt/sources.list file and ended up breaking it. I've restored it to its original contents from my backup as follows
deb http://raspbian.raspberrypi.org/raspbian/ stretch main contrib non-free rpi # Uncomment line below then 'apt-get update' to enable 'apt-get source' #deb-src http://raspbian.raspberrypi.org/raspbian/ stretch main contrib non-free rpi
Now when I run
sudo apt-get update I still get the same error message
E: Type 'deb' is not known on line 1 in source list /etc/apt/sources.list E: The list of sources could not be read.
Every other thread I've found related to this problem has said that it's a malformed line and it can be fixed by restoring the contents, but having looked at every single character with my eyelids peeled back, I can't see any differences from the original contents.
How can I fix this problem?