Spree: heroku deployment error

Question

I continue to monitor:

remote:        Gem::InstallError: spree_core requires Ruby version >= 2.1.0.
remote:        An error occurred while installing spree_core (3.0.4), and Bundler cannot
remote:        continue.
remote:        Make sure that `gem install spree_core -v '3.0.4'` succeeds before bundling.

when i run

gem install spree_code -v '3.0.4' 

it is successful, and then when I run git, click the hero master again, I get exactly the same error.

rbenv versions 

shows the following:

2.2.2 (set by /Users/Martijn/.rbenv/version)

Answer 1

Heroku needs ruby version defined in the Gemfile, for example ruby "2.2.1". Additional information: https://devcenter.heroku.com/articles/ruby-versions .