问题 I want to upload my new app to Heroku, but I'm facing some problems. At first, the problem was SQLite, so I deleted the sqlite line in my Gemfile . Another problem is that when I write in console the command git push heroku , I see this error: error: failed to push some refs. Gemfile source 'https://rubygems.org' # Bundle edge Rails instead: gem 'rails', github: 'rails/rails' gem 'rails', '4.0.0' group :production do gem 'pg' gem 'rails_12factor' end # Use SCSS for stylesheets gem 'sass-rails