$ bundle install Gem::Ext::BuildError: ERROR: Failed to build gem native extension. (abridgement) An error occurred while installing ffi (1.13.0), and Bundler cannot continue. Make sure that `gem install ffi -v '1.13.0'` succeeds before bundling. In Gemfile: guard-rspec was resolved to 4.7.3, which depends on guard was resolved to 2.16.2, which depends on listen was resolved to 3.2.1, which depends on rb-inotify was resolved to 0.10.1, which depends on ffi
$ gem install ffi -v '1.13.0' Building native extensions. This could take a while... ERROR: Error installing ffi: ERROR: Failed to build gem native extension. ...
Even if the command is executed according to the error, an error occurs
$ xcode-select --install xcode-select: error: command line tools are already installed, use "Software Update" to install updates
It was already installed.
$ sudo xcodebuild -license accept
Solved when I executed.