"Push rejected, failed to compile Multipack app" when deploying heroku-buildpack-nodejs and heroku-buildpack-ruby-minimal - heroku

Question

I'm using heroku-buildpack-multi:
BUILDPACK_URL=https://github.com/ddollar/heroku-buildpack-multi.git
I'm trying to deploy with two buildpacks and am getting the following error:
Fetching repository, done.
Counting objects: 6, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (3/3), done.
Writing objects: 100% (3/3), 325 bytes | 0 bytes/s, done.
Total 3 (delta 2), reused 0 (delta 0)
-----> Fetching custom git buildpack... done
-----> Multipack app detected
=====> Downloading Buildpack: https://github.com/heroku/heroku-buildpack-nodejs.git
! Push rejected, failed to compile Multipack app
Here are the contents of my .buildpack
https://github.com/heroku/heroku-buildpack-nodejs.git
https://github.com/dpiddy/heroku-buildpack-ruby-minimal.git
It used to be intermittent but it's now happening every time I try to deploy.
Strangely enough, the official heroku ruby project seems to have gone missing...
https://github.com/heroku/heroku-buildpack-ruby
Note that it is still on this page: https://github.com/heroku

Answer 1

You need a package.json for the node buildpack. So, something like:
{
"private": true,
"name": "my-rad-proj",
"version": "0.1.0",
"engines": {
"node": "~0.10.21"
}
}
As well as the Gemfile for ruby.