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bundle exec rails serverでbin/rails:6: warning: already initialized constant APP_PATH

More than 5 years have passed since last update.


bundle exec rails serverを入力するとWEBrinkが起動しない。


  • 以下を実行
rake rails:update:bin
  • 以下のエラーがでる…
'mysql2' for database adapter, but the gem is not loaded. Add `gem 'mysql2'` to your Gemfile


  • Gemfileに以下を追記
gem 'mysql2', '~> 0.3.20'
  • bundle installを実行
bundle install
  • bin/以下を更新
rake rails:update:bin
bundle exec rails server
  • 起動した!mysql2のバージョンアップに伴って、不具合が発生していると書いてありました。


Rails mysql2でrake db:createがエラー問題 - Qiita

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