Heroku: rake aborted - ruby-on-rails

Question

I'm trying to run db:migrate on Heroku (app's working fine locally) and I get this error:
rake aborted!
uninitialized constant Bootstrap::Rails::Engine::Sass
/app/vendor/bundle/ruby/2.0.0/bundler/gems/bootstrap-rails-8eb1287f94b3/lib/bootstrap-rails/engine.rb:6:in `block in <class:Engine>'
/app/vendor/bundle/ruby/2.0.0/gems/railties-4.0.0/lib/rails/initializable.rb:30:in `instance_exec'
/app/vendor/bundle/ruby/2.0.0/gems/railties-4.0.0/lib/rails/initializable.rb:30:in `run'
/app/vendor/bundle/ruby/2.0.0/gems/railties-4.0.0/lib/rails/initializable.rb:55:in `block in run_initializers'
/app/vendor/bundle/ruby/2.0.0/gems/railties-4.0.0/lib/rails/initializable.rb:54:in `run_initializers'
/app/vendor/bundle/ruby/2.0.0/gems/railties-4.0.0/lib/rails/application.rb:215:in `initialize!'
/app/vendor/bundle/ruby/2.0.0/gems/railties-4.0.0/lib/rails/railtie/configurable.rb:30:in `method_missing'
/app/config/environment.rb:5:in `<top (required)>'
/app/vendor/bundle/ruby/2.0.0/gems/railties-4.0.0/lib/rails/application.rb:189:in `require_environment!'
/app/vendor/bundle/ruby/2.0.0/gems/railties-4.0.0/lib/rails/application.rb:249:in `block in run_tasks_blocks'
Tasks: TOP => db:migrate => environment
(See full trace by running task with --trace)
Gemfile:
source 'https://rubygems.org'
ruby "2.0.0"
gem 'rails', '4.0.0'
# Gems used only for assets and not required
# in production environments by default.
group :assets do
gem 'sass-rails'
gem 'coffee-rails'
# See https://github.com/sstephenson/execjs#readme for more supported runtimes
# gem 'therubyracer', :platforms => :ruby
#gem 'therubyracer'
#gem 'less-rails'
#gem 'twitter-bootstrap-rails'
gem 'uglifier', '>= 1.0.3'
end
gem 'anjlab-bootstrap-rails', :require => 'bootstrap-rails',
:github => 'anjlab/bootstrap-rails',
:branch => '3.0.0'
gem 'railties', '>=4.0.0'
gem 'protected_attributes'
gem 'jquery-rails'
gem 'foreman'
# PostgreSQL
gem 'pg'
# Use Unicorn as the app server
gem 'unicorn'
# Devise for user accounts management
gem 'devise'
# Stripe for processing payments
gem 'stripe'
# New Relic monitoring
gem 'newrelic_rpm'
# QR Code generation
gem 'rqrcode-rails3'
# User auth
gem 'cancan'
group :development do
gem 'debugger'
gem 'better_errors'
gem "binding_of_caller"
gem 'meta_request'
end

Answer 1

Remove the assets group, as it doesn't exist in Rails4 anymore.
Just move the gems included in it into the global space
# Gems used only for assets and not required
# in production environments by default.
group :assets do
gem 'sass-rails'
gem 'coffee-rails'
# See https://github.com/sstephenson/execjs#readme for more supported runtimes
# gem 'therubyracer', :platforms => :ruby
#gem 'therubyracer'
#gem 'less-rails'
#gem 'twitter-bootstrap-rails'
gem 'uglifier', '>= 1.0.3'
end
# becomes
# group :assets do
gem 'sass-rails'
gem 'coffee-rails'
# See https://github.com/sstephenson/execjs#readme for more supported runtimes
# gem 'therubyracer', :platforms => :ruby
#gem 'therubyracer'
#gem 'less-rails'
#gem 'twitter-bootstrap-rails'
gem 'uglifier', '>= 1.0.3'
# end