Unable to install gem - Failed to build gem native extension - cannot load such file -- mkmf (LoadError)

Question

Ruby 1.9.3

The part of Gemfile

#...............
gem "pony"
gem "bcrypt-ruby", :require => "bcrypt"
gem "nokogiri" 
#..................

When I'm trying to install gems, I get an error

alex@ubuntu:~/$ bundle
Fetching gem metadata from http://rubygems.org/.........
Fetching gem metadata from http://rubygems.org/..
Enter your password to install the bundled RubyGems to your system: 
#####............................................................
Installing bcrypt-ruby (3.0.1) with native extensions 
Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.

        /usr/bin/ruby1.9.1 extconf.rb 
/usr/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require': cannot load such file -- mkmf (LoadError)
        from /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
        from extconf.rb:36:in `<main>'


Gem files will remain installed in /home/alex/.bundler/tmp/5526/gems/bcrypt-ruby-3.0.1 for inspection.
Results logged to /home/alex/.bundler/tmp/5526/gems/bcrypt-ruby-3.0.1/ext/mri/gem_make.out
An error occurred while installing bcrypt-ruby (3.0.1), and Bundler cannot continue.
Make sure that `gem install bcrypt-ruby -v '3.0.1'` succeeds before bundling.

Then I'm doing this

sudo gem install bcrypt-ruby -v '3.0.1'
Building native extensions.  This could take a while...
ERROR:  Error installing bcrypt-ruby:
        ERROR: Failed to build gem native extension.

        /usr/bin/ruby1.9.1 extconf.rb
/usr/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require': cannot load such file -- mkmf (LoadError)
        from /usr/lib/ruby/1.9.1/rubygems/custom_require.rb:36:in `require'
        from extconf.rb:36:in `<main>'


Gem files will remain installed in /var/lib/gems/1.9.1/gems/bcrypt-ruby-3.0.1 for inspection.
Results logged to /var/lib/gems/1.9.1/gems/bcrypt-ruby-3.0.1/ext/mri/gem_make.out

and getting an error as well.

What did I miss?

Answer 1

There are similar questions:

• `require': no such file to load -- mkmf (LoadError)
• Failed to build gem native extension (mkmf (LoadError)) - Ubuntu 12.04

Usually, the solution is:

sudo apt-get install ruby-dev

Or, if that doesn't work, depending on your ruby version, run something like:

sudo apt-get install ruby1.9.1-dev

Should fix your problem.

---

Still not working? Try the following after installing ruby-dev:

sudo apt-get install make