Phoenix error: module not loaded/not available

I think you should try to clean up deps, then get and compile again before up sever

so try

mix deps.clean --all
mix deps.get
mix deps.compile
mix phoenix.server

Good luck

You could also delete the _build directory and restart your server with mix phoenix.server (Phoenix 1.2) or mix phx.server (Phoenix 1.3).

Doing this will fetch all dependencies from scratch for the first time. I prefer this method as I don't need to type a bunch of commands, I just need to delete a directory and re-run the recent command on my terminal..which is mix phx.server. Yeah, I'm lazy.

Good luck.

You've got typo in https://github.com/bordeltabernacle/learning-phoenix/blob/master/rumbl/web/controllers/auth.ex

import Comeonin.Bcypt, only: [checkpw: 2]

should be

import Comeonin.Bcrypt, only: [checkpw: 2]