bundlerでbinstubしたrailsコマンドやrakeコマンドを使っていると、次のような警告がbin/rails cしたときなどに表示される: Looks like your app's ./bin/rails is a stub that was generated by Bundler. In Rails 4, your app's bin/ directory contains executables that are versioned like any other source code, rather than stubs that are generated on demand. Here's how to upgrade: bundle config --delete bin # Turn off Bundler's stub generator rake rail