[ruby-on-rails] Unable to install gem - Failed to build gem native extension - cannot load such file -- mkmf (LoadError)

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?

What ended up working for me after a few hours of pain..

if you're running brew..

brew install ruby

in the terminal output/log, identify the path where ruby was installed, brew suggests 'You may want to add this to your PATH', so that's what we'll do. For example, mine is

/usr/local/lib/ruby/gems/3.0.0/bin

Add this to your path by running (omitting braces)

echo 'export PATH"{the_path_you_found_above}:$PATH"' >> ~/.bash_profile

then update your environment by running

source ~/.bash_profile

now, try running your install, i.e.,

sudo gem install middleman

I created a small hackMD to install cocoapods on MacOS 10.15 (Catalina) and 11 (Big Sur)

https://hackmd.io/@sBJPlhRESGqCKCqV8ZjP1A/S1UY3W7HP

Installing Cocoapods on MacOS Catalina(MacOS 10.15.X) and Big Sur (MacOS 11)

1. Make sure you have xcode components are installed.

2. Download 'Command Line Tools' (about 500MB) directly from this link (Requires you to have apple account) https://developer.apple.com/downloads/index.action

3. Install the downloaded file

4. Click on Install

5. Install COCOAPODS files in terminal sudo gem install -n /usr/local/bin cocoapods

After some search for a solution, it turns out the -dev package is needed, not just ruby1.8. So if you have ruby1.9.1 doing

sudo apt-get install ruby1.9.1-dev

or to install generic ruby version, use (as per @lamplightdev comment):

sudo apt-get install ruby-dev

should fix it.

Try to locate mkmf to see if the file is actually there.

1. Make sure ruby-dev is installed
2. Make sure make is installed
3. If you still get the error, look for suggested packages. If you are trying to install something like gem install pg you will also need to install the lib libpq-dev (sudo apt-get install libpq-dev).

I had the same issue trying to install jquery-rails. The fix was

sudo apt-get install zlibc zlib1g zlib1g-dev

I found that I needed to install another version of ruby. So running the command

$ sudo apt-get install ruby1.9.1-dev

and then attempt to install the extension

If you run into issues where it is telling you that you don't have g++ you can run the following command to install it

$ sudo apt-get install g++

In Mac, for me this works:

CONFIGURE_OPTS="--enable-shared" rbenv install 2.2.2

For MacOS users:

Just do this and easily it will solve your problem:

brew install cocoapods

This worked for me. bundle config --global build.snappy --with-opt-dir="$(brew --prefix snappy)"

In case anyone in the future had this problem, I'm using a Mac and just had to install the Command Line Tools using 'xcode-select --install'

Just finished a 2 hour wild goose chase trying to solve this. None of the posted answers worked for me. Im on a Mac (Mojave Version 10.14.6, Xcode Version 11.3).

It turns out the ruby file headers were missing so i had to run open /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg

That didnt work for me at first because the version of CommandLineTools i had installed did not have the "Packages" folder. So i uninstalled and reinstalled like this:

rm -rf /Library/Developer/CommandLineTools

xcode-select --install

Then i ran the previous command again:

open /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg

After install the error was fixed!

It also helps to ensure libmysqlclient-dev is installed (Ubuntu 14.04)

For WSL (Windows Subsystem for Linux) you need install build-essential package:

sudo apt install build-essential