Errors when trying to start a new Rails app with Spree Commerce

I am getting the following error when trying to install Spree Commerce (a clean install) into a new rails application.

Could not load generator "generators/spree/install/install_generator". Error: uninitialized constant Bundler::Thor::Base.

Any help would be greatly appreciated! I have already checked the resources on the SpreeCommerce Documentation, Spree's Github, and similar issues that have come up and those solutions do not work for me.

Edit: Here is my gemfile:

source 'https://rubygems.org'


# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
gem 'rails', '4.2.0'
# Use sqlite3 as the database for Active Record
gem 'sqlite3'
# Use SCSS for stylesheets
gem 'sass-rails', '~> 5.0'
# Use Uglifier as compressor for JavaScript assets
gem 'uglifier', '>= 1.3.0'
# Use CoffeeScript for .coffee assets and views
gem 'coffee-rails', '~> 4.1.0'
# See https://github.com/sstephenson/execjs#readme for more supported runtimes
# gem 'therubyracer', platforms: :ruby

# Use jquery as the JavaScript library
gem 'jquery-rails'
# Turbolinks makes following links in your web application faster. Read more: https://github.com/rails/turbolinks
gem 'turbolinks'
# Build JSON APIs with ease. Read more: https://github.com/rails/jbuilder
gem 'jbuilder', '~> 2.0'
# bundle exec rake doc:rails generates the API under doc/api.
gem 'sdoc', '~> 0.4.0', group: :doc

# Use ActiveModel has_secure_password
# gem 'bcrypt', '~> 3.1.7'

# Use Unicorn as the app server
# gem 'unicorn'

# Use Capistrano for deployment
# gem 'capistrano-rails', group: :development

group :development, :test do
  # Call 'byebug' anywhere in the code to stop execution and get a debugger console
  gem 'byebug'

  # Access an IRB console on exception pages or by using <%= console %> in views
  gem 'web-console', '~> 2.0'

  # Spring speeds up development by keeping your application running in the background. Read more: https://github.com/rails/spring
  gem 'spring'
end


gem 'spree', '3.0.1'
gem 'spree_gateway', github: 'spree/spree_gateway', branch: '3-0-stable'
gem 'spree_auth_devise', github: 'spree/spree_auth_devise', branch: '3-0-    stable'

Here are the commands I have tried (all on clean new rails apps...all have the same resulting error as above):

1) I've tried using the methods listed on Spree's github page:

$ gem install spree
$ rails _4.2.1_ new my_store
$ spree install my_store

2) I've tried adding spree gem manually to a new apps gemfile, and then:

$ bundle install
$ rails g spree:install --sample=false --seed=false

3) I've tried following the steps as outlined on the spreecommerce tutorial:

$ gem install spree_cmd
$ rails new mystore
$ spree install --auto-accept

Solution

Solved the issue. Seems like it had something to do with RVM.

I fixed it by creating a new gemset (although based on the same version of Ruby I was currently using), and creating a new rails app with that specific gemset.

I then added spree to my gemfile, and ran the following commands:

$ bundle install
$ rails g spree:install --sample=false --seed=false