ERROR: ‘rake/rdoctask’ is obsolete and no longer supported. Use ‘rdoc/task’ (available in RDoc 2.4.2+) instead

I had similar problem using rails 2.3.5 so as instructed in the trace message I have edited the Rakefile to require ‘rdoc/task’ instead of rake/rdoctask and installed rdoc gem.

If you are using rake version > 10.0.0 . please edit your Rakefile

from:

require 'rake'
require 'rake/testtask'
require 'rake/rdoctask'
require 'tasks/rails'

to:

require 'rake'
require 'rake/testtask'
require 'rdoc/task'
require 'tasks/rails'

If you don’t want to edit the Rakefile you can switch back to older version of take like this

gem uninstall rake -v 10.0.3
gem install rake -v 0.8.7