質問: gem 'mysql2', '>= 0.3.18', '< 0.5' ターミナル Fetching mysql2 0.4.10 Installing mysql2 0.4.10 with native extensions Gem::Ext::BuildError: ERROR: Failed to build gem native extension. 省略... Gem files will remain installed in /Users/makmzw/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/mysql2-0.4.10 for inspection. Results logged to /Users/makmzw/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/extensions/x86_64-darwin-16/2.3.0-static/mysql2-0.4.10/gem_make.out An error occurred while installing mysql2 (0.4.10), and Bundler cannot continue. Make sure that `gem install mysql2 -v '0.4.10'` succeeds before bundling. In Gemfile: mysql2 変更後: gem 'mysql2', '>= 0.4.10', '< 0.5' ターミナル: bundle install 同様のエラーが出ます。 An error occurred while installing mysql2 (0.4.10), and Bundler cannot continue. Make sure that `gem install mysql2 -v '0.4.10'` succeeds before bundling.
回答: パスが通っていませんでした。