I made a rails project with,

rails new test_bootstrap.

succeeded.

moved to the project dir and added the gems

gem "therubyracer"
gem "less-rails" #Sprockets (what Rails 3.1 uses for its asset pipeline) supports LESS
gem "twitter-bootstrap-rails"

and run

bundle install

after that, i have this error.

Installing libv8 (3.16.14.3)
Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.

c:/RailsInstaller/Ruby1.9.3/bin/ruby.exe extconf.rb
creating Makefile
지정된 경로를 찾을 수 없습니다.                                                          지정된 경로를 찾을 수
없습니다.                                                          지정된 경로를 찾을 수 없습니다.

c:/RailsInstaller/Ruby1.9.3/lib/ruby/ge
ms/1.9.1/gems/libv8-3.16.14.3/ext/libv8/builder.rb:58:in `setup_python!': libv8 requires
python 2 to be installed in order to build, but it is currently not available (RuntimeErr
or) from c:/RailsInstaller/Ruby1.9.
3/lib/ruby/gems/1.9.1/gems/libv8-3.16.14.3/ext/libv8/builder.rb:42:in `block in build_lib
v8/builder.rb:42:in `block in build_libv8!'
        from c:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/libv8-3.16.14.3/ext/lib
v8/builder.rb:40:in `chdir'
        from c:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/libv8-3.16.14.3/ext/lib
v8/builder.rb:40:in `build_libv8!'
        from c:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/libv8-3.16.14.3/ext/lib
v8/location.rb:24:in `install!'
        from extconf.rb:7:in `<main>'                                                    


Gem files will remain installed in c:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/l
ibv8-3.16.14.3 for inspection.
Results logged to c:/RailsInstaller/Ruby1.9.3/lib/ruby/gems/1.9.1/gems/libv8-3.16.14.3/ex
t/libv8/gem_make.out
An error occurred while installing libv8 (3.16.14.3), and Bundler cannot
continue.
Make sure that `gem install libv8 -v '3.16.14.3'` succeeds before bundling.

sorry for some Koreans. It says, It can't find the chosen path or something like that.

and i tried to run this command

gem install libv8 -v '3.16.14.3'

throwing the same error.

Gopal S Rathore

try this one:

gem install libv8 -v '3.16.14.3' -- --with-system-v8

Note : Because libv8 is the interface for the V8 engine used by therubyracer, you may need to use libv8, even if you have V8 installed already. If you wish to use your own V8 installation, rather than have it built for you, use the --with-system-v8 option.

For more you can go through the documentation of libv8 on github

Arpit Shah

How to resolve libv8/therubyracer issue

I encountered similar issue in which after installing libv8, error occurs installing therubyracer. Here is my solution:

$ gem install libv8 -v '3.16.14.3' -- --with-system-v8

$ bundle install

-- see error installing therubyracer --

$ gem uninstall libv8

$ brew install v8

$ gem install therubyracer

$ bundle install

-- see error installing libv8 --

$ gem install libv8 -v '3.16.14.3' -- --with-system-v8

With homebrew this helps me to solve this error.

brew tap homebrew/versions
brew install v8-315

gem install libv8 -v '3.16.14.13' -- --with-system-v8
gem install therubyracer -- --with-v8-dir=/usr/local/opt/v8-315

bundle install

Seen on rubyracer Github issues.

I tried the solution listed above command which looks very fine for installing individual gem, but for bundler users - you should use bundle config

Use

bundle config build.libv8 --with-system-v8

and

bundle config build.therubyracer --with-system-v8

to configure bundler to take the parameters to be used while installing specific gem

Litmus

I do not think you need therubyracer gem on windows. It is a javascript runtime using V8 engine. Hence it is making an attempt to install libv8.

You can safely remove the gem from your Gemfile.

Rails is happy to use which ever runtime it can find. execjs,nodejs etc. are all possible options.

Microsoft already embeds JScript runtime for javascript on windows, and Rails uses it. See this for more

Other workaround to fix the problem is to separate them in the Gemfile

group :production do
 gem 'libv8', '~> 3.11.8.3'
 gem 'therubyracer', :platform => :ruby
end

And then run the bundle command: bundle install --without production

That works for me. Put that in your Gemfile

gem 'libv8', '~>3.16.14.7'

I was also unable to install this gem instead of using

--with-system-v8

once try to do bundle update which worked fine for me

My issue wasn't related with therubyracer at all just libv8 gem and as @rishav-bhardwaj pointed --with-system-v8 didn't do the trick, instead i had to exec

bundle update

then

bundle install

and finally

Bundle complete!

The error is gone!

Gem::Ext::BuildError: ERROR: Failed to build gem native extension. An error occurred while installing libv8 (3.16.14.7), and Bundler cannot continue. Make sure that `gem install libv8 -v '3.16.14.7'` succeeds before bundling.

Try with

gem "therubyracer", "~> 0.10.2" to Gemfile

And it will install dependent gem libv8 (3.3.10.4) and the issue of build gem native extension failure got resolve.

Resolved libv8 3.16.14.7 issue using below command:

gem install libv8 -v '3.16.14.7' -- --with-system-v8

And then bundle install successfully completed.

i feel this has less to do with libv8 and more to do with therubyracer.

i received your same error while running a bundle install on a rails app. if you have encountered this similarly, try installing the gem outside of bundle like so:

gem install therubyracer

then run bundle install. i hope this works for you too.

来源：https://stackoverflow.com/questions/19673714/error-installing-libv8-error-failed-to-build-gem-native-extension

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ruby-on-rails