Bundler on Ubuntu 16.04 yields the following error when trying to install JSON.
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.
current directory: /tmp/bundler20170601-12986-10dsu07json-1.8.6/gems/json-1.8.6/ext/json/ext/generator
/usr/bin/ruby2.3 -r ./siteconf20170601-12986-op73sp.rb extconf.rb
mkmf.rb can't find header files for ruby at /usr/lib/ruby/include/ruby.h
extconf failed, exit code 1
Gem files will remain installed in /tmp/bundler20170601-12986-10dsu07json-1.8.6/gems/json-1.8.6 for inspection.
Results logged to /tmp/bundler20170601-12986-10dsu07json-1.8.6/extensions/x86_64-linux/2.3.0/json-1.8.6/gem_make.out
An error occurred while installing json (1.8.6), and Bundler cannot continue.
Make sure that `gem install json -v '1.8.6'` succeeds before bundling.
In Gemfile:
react-rails was resolved to 1.7.2, which depends on
rails was resolved to 4.2.7.1, which depends on
actionmailer was resolved to 4.2.7.1, which depends on
actionpack was resolved to 4.2.7.1, which depends on
actionview was resolved to 4.2.7.1, which depends on
rails-dom-testing was resolved to 1.0.8, which depends on
rails-deprecated_sanitizer was resolved to 1.0.3, which depends on
activesupport was resolved to 4.2.7.1, which depends on
json
It looks as if the gem extensions couldn't be compiled because of lacking header files. What can I do?