ExecJS and could not find a JavaScript runtime

Just add ExecJS and the Ruby Racer in your gem file and run bundle install after.

gem 'execjs'

gem 'therubyracer'

Everything should be fine after.

Ubuntu Users

I'm on Ubuntu 11.04 and had similar issues. Installing Node.js fixed it.

As of Ubuntu 13.04 x64 you only need to run:

sudo apt-get install nodejs

This will solve the problem.

CentOS/RedHat Users

sudo yum install nodejs

In your Gem file, write

gem 'execjs'
gem 'therubyracer'

and then run

bundle install

Everything works fine for me :)

I had a similar problem: my Rails 3.1 app worked fine on Windows but got the same error as the OP when running on Linux. The fix that worked for me on both platforms was to add the following to my Gemfile:

gem 'therubyracer', :platforms => :ruby

The trick is knowing that :platforms => :ruby actually means only use this gem with "C Ruby (MRI) or Rubinius, but NOT Windows."

Other possible values for :platforms are described in the bundler man page.

FYI: Windows has a builtin JavaScript engine which execjs can locate. On Linux there is not a builtin although there are several available that one can install. therubyracer is one of them. Others are listed in the execjs README.md.

Adding the following gem to my Gemfile solved the issue:

gem 'therubyracer'

Then bundle your new dependencies:

$ bundle install