Railsチュートリアルでgit push heroku masterでデプロイできない。

Question

前提・実現したいこと

Railsチュートリアルの第2章をやっています。

git commit -am "Add hello"
heroku create
git push && git push heroku master

git pushは成功したのですが、 git push heroku master が失敗してしまいます。

発生している問題・エラーメッセージ

下記のエラーメッセージの最後の方のPush rejected to ancient-tundra-71374.がエラー箇所です。

ubuntu:~/environment/toy_app (master) $ git push && git push heroku master
Everything up-to-date
Counting objects: 117, done.
Compressing objects: 100% (99/99), done.
Writing objects: 100% (117/117), 27.26 KiB | 1.14 MiB/s, done.
Total 117 (delta 12), reused 0 (delta 0)
remote: Compressing source files... done.
remote: Building source:
remote: 
remote: -----> Building on the Heroku-20 stack
remote:  !     Warning: Multiple default buildpacks reported the ability to handle this app. The first buildpack in the list below will be used.
remote:                         Detected buildpacks: Ruby,Node.js
remote:                         See https://devcenter.heroku.com/articles/buildpacks#buildpack-detect-order
remote: -----> Ruby app detected
remote: -----> Installing bundler 1.17.3
remote: -----> Removing BUNDLED WITH version in the Gemfile.lock
remote: -----> Compiling Ruby/Rails
remote: -----> Using Ruby version: ruby-2.6.6
remote: -----> Installing dependencies using bundler 1.17.3
remote:        Running: BUNDLE_WITHOUT='development:test' BUNDLE_PATH=vendor/bundle BUNDLE_BIN=vendor/bundle/bin BUNDLE_DEPLOYMENT=1 BUNDLE_GLOBAL_PATH_APPENDS_RUBY_SCOPE=1 bundle install -j4
remote:        The dependency tzinfo-data (>= 0) will be unused by any of the platforms Bundler is installing for. Bundler is installing for ruby but the dependency is only for x86-mingw32, x86-mswin32, x64-mingw32, java. To add those platforms to the bundle, run `bundle lock --add-platform x86-mingw32 x86-mswin32 x64-mingw32 java`.
remote:        Fetching gem metadata from https://rubygems.org/............
remote:        Fetching https://github.com/rails/webpacker.git
remote:        Fetching rake 12.3.3
remote:        Installing rake 12.3.3
remote:        Fetching concurrent-ruby 1.1.8
　・・・（中略）・・・
remote:        Installing actionmailbox 6.0.3
remote:        Fetching actiontext 6.0.3
remote:        Installing actiontext 6.0.3
remote:        Using webpacker 6.0.0.beta.4 from https://github.com/rails/webpacker.git (at master@f40fa08)
remote:        Fetching sass-rails 5.1.0
remote:        Installing sass-rails 5.1.0
remote:        Fetching rails 6.0.3
remote:        Installing rails 6.0.3
remote:        Bundle complete! 18 Gemfile dependencies, 61 gems now installed.
remote:        Gems in the groups development and test were not installed.
remote:        Bundled gems are installed into `./vendor/bundle`
remote:        Post-install message from i18n:
remote:        
remote:        HEADS UP! i18n 1.1 changed fallbacks to exclude default locale.
remote:        But that may break your application.
remote:        
remote:        If you are upgrading your Rails application from an older version of Rails:
remote:        
remote:        Please check your Rails app for 'config.i18n.fallbacks = true'.
remote:        If you're using I18n (>= 1.1.0) and Rails (< 5.2.2), this should be
remote:        'config.i18n.fallbacks = [I18n.default_locale]'.
remote:        If not, fallbacks will be broken in your app by I18n 1.1.x.
remote:        
remote:        If you are starting a NEW Rails application, you can ignore this notice.
remote:        
remote:        For more info see:
remote:        https://github.com/svenfuchs/i18n/releases/tag/v1.1.0
remote:        
remote:        Post-install message from sass:
remote:        
remote:        Ruby Sass has reached end-of-life and should no longer be used.
remote:        
remote:        * If you use Sass as a command-line tool, we recommend using Dart Sass, the new
remote:          primary implementation: https://sass-lang.com/install
remote:        
remote:        * If you use Sass as a plug-in for a Ruby web framework, we recommend using the
remote:          sassc gem: https://github.com/sass/sassc-ruby#readme
remote:        
remote:        * For more details, please refer to the Sass blog:
remote:          https://sass-lang.com/blog/posts/7828841
remote:        
remote:        Bundle completed (37.47s)
remote:        Cleaning up the bundler cache.
remote: -----> Installing node-v12.16.2-linux-x64
remote: -----> Installing yarn-v1.22.4
remote: -----> Detecting rake tasks
remote: -----> Preparing app for Rails asset pipeline
remote:        Running: rake assets:precompile
remote:        yarn install v1.22.4
remote:        info No lockfile found.
remote:        [1/4] Resolving packages...
remote:        [2/4] Fetching packages...
remote:        [3/4] Linking dependencies...
remote:        [4/4] Building fresh packages...
remote:        Done in 0.63s.
remote:        I, [2021-01-24T04:20:25.605373 #1108]  INFO -- : Writing /tmp/build_4329fc4d/public/assets/application-e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855.css
remote:        I, [2021-01-24T04:20:25.606259 #1108]  INFO -- : Writing /tmp/build_4329fc4d/public/assets/application-e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855.css.gz
remote:        Compiling...
remote:        Compilation failed:
remote:        yarn run v1.22.4
remote:        info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.
remote:        
remote:        
remote:        error Command "webpack" not found.
remote:        
remote: 
remote:  !
remote:  !     Precompiling assets failed.
remote:  !
remote:  !     Push rejected, failed to compile Ruby app.
remote: 
remote:  !     Push failed
remote: Verifying deploy...
remote: 
remote: !       Push rejected to peaceful-wave-59304.
remote: 
To https://git.heroku.com/peaceful-wave-59304.git
 ! [remote rejected] master -> master (pre-receive hook declined)
error: failed to push some refs to 'https://git.heroku.com/peaceful-wave-59304.git'

試したこと

• gitとHerokuにはログイン済みです。

• Herokuのpush先のレポジトリもheroku createで作成済みです

 ubuntu:~/environment/toy_app (master) $ git remote -v
heroku  https://git.heroku.com/peaceful-wave-59304.git (fetch)
heroku  https://git.heroku.com/peaceful-wave-59304.git (push)
 origin  [e-mail]:●●●●●●/toy_app.git (fetch)　
 origin  [e-mail]:●●●●●●/toy_app.git (push)
　
　　※●はアカウント名なので伏字に

• 似たような質問があったのでyarn runをしたが効果なし。

ubuntu:~/environment/toy_app (master) $ yarn -v
1.22.5
ubuntu:~/environment/toy_app (master) $ yarn run
yarn run v1.22.5
error There are no binary scripts available.
error There are no scripts specified inside package.json.
Done in 0.05s.

• sudo apt install webpack でWebpackをインストールしなおしましたが結果は変わりませんでした。

補足情報（FW/ツールのバージョンなど）

source 'https://rubygems.org'
git_source(:github) { |repo| "https://github.com/#{repo}.git" }

gem 'rails',      '6.0.3'
gem 'puma',       '4.3.6'
gem 'sass-rails', '5.1.0'
gem 'webpacker',  '4.0.7'
# gem "webpacker", github: "rails/webpacker"
gem 'turbolinks', '5.2.0'
gem 'jbuilder',   '2.9.1'
gem 'bootsnap',   '1.4.5', require: false

group :development, :test do
  gem 'sqlite3', '1.4.1'
  gem 'byebug',  '11.0.1', platforms: [:mri, :mingw, :x64_mingw]
end

group :development do
  gem 'web-console',           '4.0.1'
  gem 'listen',                '3.1.5'
  gem 'spring',                '2.1.0'
  gem 'spring-watcher-listen', '2.0.1'
end

group :test do
  gem 'capybara',           '3.28.0'
  gem 'selenium-webdriver', '3.142.4'
  gem 'webdrivers',         '4.1.2'
end

group :production do
  gem 'pg', '1.1.4'
end

# Windows ではタイムゾーン情報用の tzinfo-data gem を含める必要があります
gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]

Comments

[hatsu]

よく見るのがRAILS_MASTER_KEYをherokuにセットしていないという原因です。セットしてありますか？心当たりなければ、セットの仕方を回答として書いておきます。

[hirow10]

有難う御座います。

RAILS_MASTER_KEYのセットはしていなかったので下記の手順でやってみましたが、同様のエラーが出てしまいました。
https://yukitoku-sw.hatenablog.com/entry/2020/02/04/145331