Cannot use db migrate when deploy to Heroku - ruby-on-rails

Question

I tried to deploy my code to heroku. It only work with
config.assets.initialize_on_precompile = false
in my application.rb despite I'm using Rails 4.2.3. But when I tried to use
heroku run rake db:migrate
It cannot work correctly with error:
Name Error: Undefined local variable or method config for main:Object
/app/config/application.rb:7 in `'
Here is my Gemfile
source 'https://rubygems.org'
# Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
gem 'rails', '4.2.3'
group :production do
#Use PG
gem 'pg'
end
group :development do
# Use sqlite3 as the database for Active Record
gem 'sqlite3'
end
# Use SCSS for stylesheets
gem 'sass-rails', '~> 5.0.1'
# Use Uglifier as compressor for JavaScript assets
gem 'uglifier', '>= 1.3.0'
# Use CoffeeScript for .js.coffee assets and views
gem 'coffee-rails', '~> 4.0.0'
# 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 Heroku
gem 'rails_12factor', group: 'production'
#Use bootstrap
gem 'bootstrap', '~> 4.0.0.alpha3'
gem 'autoprefixer-rails'
#Use Redcarpet
gem 'redcarpet'
#Use SQLite
#gem 'sqlite3', '1.3.11'
# Use Capistrano for deployment
# gem 'capistrano-rails', group: :development
# Use debugger
# gem 'debugger', group: [:development, :test]
# Windows does not include zoneinfo files, so bundle the tzinfo-data gem
gem 'tzinfo-data', platforms: [:mingw, :mswin]
And here is application.rb
require File.expand_path('../boot', __FILE__)
require 'rails/all'
# Require the gems listed in Gemfile, including any gems
# you've limited to :test, :development, or :production.
# Prevent initializing the application before assets are precompiled (required for heroku)
config.assets.initialize_on_precompile = false
Bundler.require(*Rails.groups)
module Blog
class Application < Rails::Application
# Settings in config/environments/* take precedence over those specified here.
# Application configuration should go into files in config/initializers
# -- all .rb files in that directory are automatically loaded.
# Set Time.zone default to the specified zone and make Active Record auto-convert to this zone.
# Run "rake -D time" for a list of tasks for finding time zone names. Default is UTC.
# config.time_zone = 'Central Time (US & Canada)'
# The default locale is :en and all translations from config/locales/*.rb,yml are auto loaded.
# config.i18n.load_path += Dir[Rails.root.join('my', 'locales', '*.{rb,yml}').to_s]
# config.i18n.default_locale = :de
end
end
Any solutions for my stuck point?
The log when I tried : git push heroku master with
config.assets.initialize_on_precompile = false
put in production.rb
http://i.stack.imgur.com/9rXp9.png
Sorry I cannot put img since I'm newbie.

Answer 1

Remove config.assets.initialize_on_precompile = false from application.rb
If you need to have this line in your rails application it should go in: app/config/environments/production.rb