I did some experimenting and found something odd. I’m new to Phoenix and Elixir too, so no idea what’s going on either
I went through the same tutorial and got it working, so to get your error I deleted the show.html.heex file. I then restored the show.html.heex file and the error doesn’t get resolved despite it being restored to the previously working state.
By any chance have you put below in the Index.html.heex as well as the show.html.heex?
Hello World, from <%= @messenger %>!
I was lazy and copied it into both html.heex files the first time I did the tutorial and it failed. I deleted this from the index and show files then restarted the server everything started working again. Try deleting everything in both the html.heex files in the hello folder and restart your server to see if you can get the routes working as they don’t need any of the html information to work.
I commented out the contents of the index.html.heex file and it magically “fixed” the problem.
This is a big error on the part of the phoenix developers - or whomever is responsible for this part of the app. I am not sure how to reproduce the error otherwise I would put in a ticket at Github.
They’re probably already aware of it - hopefully!