ERROR: 'rake/rdoctask' is obsolete and no longer supported

Question

Out of the blue, I started getting the following error message:

(in /Users/me/.rvm/gems/ruby-1.9.3-p125@mysql2/gems/rails-0.9.5)
rake aborted!
ERROR: \'rake/         


        

Answer 1

Upgrading to rails 4.0.0 I got the same error.

rails -v
(in /Users/oma/.rvm/gems/ruby-2.0.0-p247/gems/rails-0.9.5)
rake aborted!
ERROR: 'rake/rdoctask' is obsolete and no longer supported. Use 'rdoc/task' (available in RDoc 2.4.2+) instead.
/Users/oma/.rvm/gems/ruby-2.0.0-p247/gems/rails-0.9.5/Rakefile:3:in `'
(See full trace by running task with --trace)

To upgrade, I removed the version number in Gemfile

 source 'https://rubygems.org'
 gem 'rails'   # NO VERSION

and did bundle update as I thought this would pick the last. But somehow, I got rails 0.9.5. It feels like some practical joke, really, lol

$ gem list rails
rails (4.0.1.rc2, 4.0.0, 0.9.5)

I can't tell you with 100% certainty that this was the cause, but we were two people, working on the same branch and seeing the same error. The fix worked for both of us. Simply

specify rails version!

$gem uninstall rails -v 0.9.5
Gemfile
  source 'https://rubygems.org'
  gem 'rails', '4.0.0'

then bundle, run rails -v, giggle (or cry) and get back to producing