uninitialized constant Rake::DSL Ruby Windows Solution

Today, when trying to create a sample application in Ruby on Rails on a Windows operating System, I encountered the following exception:
uninitialized constant Rake::DSL
In this blog post, I will address how I came over this issue and successfully used rake db:migrate command. I'm a beginner myself to Ruby on Rails, and hope this note serve as handy to somebody who is encountering a similar issue on Rake. My Ruby version is 1.9.2 and Rails is running on version 3.0.7. The complete error message I got in my case is provided below;
rake aborted!
uninitialized constant Rake::DSL
C:/Ruby192/lib/ruby/1.9.1/rake.rb:2482:in `const_missing'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/rake-0.9.1/lib/rake/tasklib.rb:8:in `'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/rake-0.9.1/lib/rake/tasklib.rb:6:in `'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/rake-0.9.1/lib/rake/tasklib.rb:3:in `'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/rake-0.9.1/lib/rake/rdoctask.rb:20:in `require'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/rake-0.9.1/lib/rake/rdoctask.rb:20:in `'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.0.7/lib/rails/tasks/documentation.rake:1:in `require'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.0.7/lib/rails/tasks/documentation.rake:1:in `'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.0.7/lib/rails/tasks.rb:15:in `load'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.0.7/lib/rails/tasks.rb:15:in `block in '
C:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.0.7/lib/rails/tasks.rb:6:in `each'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.0.7/lib/rails/tasks.rb:6:in `'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.0.7/lib/rails/application.rb:214:in `require'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.0.7/lib/rails/application.rb:214:in `initialize_tasks'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.0.7/lib/rails/application.rb:139:in `load_tasks'
C:/Ruby192/lib/ruby/gems/1.9.1/gems/railties-3.0.7/lib/rails/application.rb:77:in `method_missing'
C:/myruby/blog/Rakefile:7:in `'
C:/Ruby192/lib/ruby/1.9.1/rake.rb:2373:in `load'
C:/Ruby192/lib/ruby/1.9.1/rake.rb:2373:in `raw_load_rakefile'
C:/Ruby192/lib/ruby/1.9.1/rake.rb:2007:in `block in load_rakefile'
C:/Ruby192/lib/ruby/1.9.1/rake.rb:2058:in `standard_exception_handling'
C:/Ruby192/lib/ruby/1.9.1/rake.rb:2006:in `load_rakefile'
C:/Ruby192/lib/ruby/1.9.1/rake.rb:1991:in `run'
C:/Ruby192/bin/rake:31:in `<<main>'
Now, the first step I took towards solving this problem is to issue "bundle update rake" command to update my rake. This will update rake to the latest version. An example log for this update is provided below;
bundle update rake
Fetching source index for http://rubygems.org/
Using rake (0.9.1)
Using abstract (1.0.0)
Using activesupport (3.0.7)
Using builder (2.1.2)
Using i18n (0.5.0)
Using activemodel (3.0.7)
Using erubis (2.6.6)
Using rack (1.2.3)
Using rack-mount (0.6.14)
Using rack-test (0.5.7)
Using tzinfo (0.3.27)
Using actionpack (3.0.7)
Using mime-types (1.16)
Using polyglot (0.3.1)
Using treetop (1.4.9)
Using mail (2.2.19)
Using actionmailer (3.0.7)
Using arel (2.0.10)
Using activerecord (3.0.7)
Using activeresource (3.0.7)
Using bundler (1.0.14)
Using thor (0.14.6)
Using railties (3.0.7)
Using rails (3.0.7)
Using sqlite3 (1.3.3)
Your bundle is updated! Use `bundle show [gemname]` to see where a bundled gem i
s installed.
Now,Once this step is done you can check the version of Rake by using the command "bundle show rake". The version of Rake came out to be 0.9.1. Now, inside your application you need to edit your Rakefile as shown below;
require File.expand_path('../config/application', __FILE__)
require 'rake'
#Use correct application name that matches for you
module ::Blog
  class Application
    include Rake::DSL

module ::RakeFileUtils
  extend Rake::FileUtilsExt

If you have done these steps properly, and then issue rake db:migrate, it should all work fine for you. Give a try and let us know. Check out these great book on Rails,


  1. Also had to add require 'rake/dsl_definition' above require 'rake' in your Rakefile

  2. +1 for what iagot said. I had to do the same addition to get it to work.

  3. I did all that. But nothing works. Can you please advise me something.

  4. Thanks guys for posting in such a details. I have done all that and nothing worked. I am using rake 0.9.2. Whole code and app works fine with 0.8.7 rake version. However, I am seriouly stuggling with deploying with these versions.

    Any feedback if there is a simpler way to deploy an app. Thanks in advance. Amol

  5. @takaloosingh,

    Can you post an extract of the error message along with the version details?

  6. didn't work for me either.

    "rake aborted!
    couldn't parse YAML at line 6 column 0....."

    my rake version is 0.9.2

  7. Check http://stackoverflow.com/questions/4980877/rails-error-couldnt-parse-yaml

    It solve for me.