The wget script has thrown a 404 for several weeks now. During this time, I've run it when it actually worked maybe once?
Likely a conincidence, but when I started running pre-releases, within the last month or so, I started noticing this error, since I've updates have occurred more frequently.
Attempting to uncheck "Get pre-releases," rename VERSION (which says 1.3.18), and rename the AppImage and then run the script hasn't helped.
Can you copy and paste an example of it failing? I tested on my computer using the below command (copy and pasted from the README) and it worked fine.
wget -O - https://raw.githubusercontent.com/laurent22/joplin/dev/Joplin_install_and_update.sh | bash
--2020-11-18 15:00:47-- https://raw.githubusercontent.com/CalebJohn/joplin/arch-check/Joplin_install_and_update.sh
Resolving raw.githubusercontent.com (raw.githubusercontent.com)... 151.101.196.133
Connecting to raw.githubusercontent.com (raw.githubusercontent.com)|151.101.196.133|:443... connected.
HTTP request sent, awaiting response... 404 Not Found
2020-11-18 15:00:48 ERROR 404: Not Found.
Looks like you're running a different wget command and not the official one. Can I ask where you got the command from? I ask because it looks like you're pulling the script from my personal fork of Joplin, and specifically from a development branch which was deleted on March 24th...
If you run the command I pasted above it will work for you.
That's a great start. The official script works for release versions.
How to run it with --prerelease?; that is, without first downloading the script and then running it? [Edit] Yes, bash -s -- --prerelease
I don't recall exactly where I got the other script but probably on a form or blog--clearly not where I should have.
I don't recall exactly where I got the other script but probably on a form or blog--clearly not where I should have.
I was just curious, it's just funny to see your own username in someone else's error log 
Glad to see you got it working!