I already pushed a Play app before, so I don't understand why I'm getting this error now on another app:
git push heroku master
...
-----> Heroku receiving push
! Heroku push rejected, no Cedar-supported app detected
This question doesn't seem to be relevant, since I don't have a Gemfile (my other app pushes quite fine without one). At first I had a Procfile as instructed here, but then I noticed my other working app does't have a Procfile, so I removed it.
Here is the working app, and the problematic one.
The remote git config is
[remote "heroku"]
url = git@heroku.com:bitcoinpotato.git
fetch = +refs/heads/*:refs/remotes/heroku/*
The app stack is the latest - cedar.