Could not update rails - ruby-on-rails-3

Question

When I do bundle update rails, I get this error:
Bundler could not find compatible versions for gem "activesupport":
In Gemfile:
rails (= 3.2.11) x86-mingw32 depends on
activesupport (= 3.2.11) x86-mingw32
activesupport (3.1.0)
here is my gemFile, any help is apprecaited :)
source 'http://rubygems.org'
gem 'rails' , '3.2.11'
gem "heroku"
gem 'thin'
gem 'devise'#, '1.5.2'
gem 'will_paginate', '~> 3.0.2'
#gem 'nested_form', :git => 'git://github.com/fxposter/nested_form.git'
gem "simple_form"
gem "cancan"
gem 'kaminari'
gem 'foreigner'
gem "cocoon"
gem 'client_side_validations'
# Gems used only for assets and not required
# in production environments by default.
group :assets do
gem 'sass-rails', " ~> 3.1.0"
gem 'coffee-rails', "~> 3.1.0"
gem 'uglifier'
end
gem "jquery-rails"
gem "validate_url", "~> 0.2.0"
gem 'pg', :group => [:production]
gem 'haml'
# Use unicorn as the web server
# gem 'unicorn'
# Deploy with Capistrano
# gem 'capistrano'
# To use debugger
# gem 'ruby-debug19', :require => 'ruby-debug'
group :test, :development do
gem 'sqlite3'
gem 'turn', :require => false
gem "rspec-rails", "2.7"
#gem "rspec"
gem "spork", "> 0.9.0.rc"
gem 'guard-spork'
#gem "webrat", "~> 0.7.3"
gem 'rb-fsevent' # Not mandatory for guard to work, which is why it's not a dependency, but it is an optimization
#gem "guard-spork"
#gem 'minitest'
gem "factory_girl_rails", "~> 1.2"
#gem "webrat-rspec-rails"
gem "mocha"
gem 'capybara' #, :git => 'git://github.com/jnicklas/capybara.git'
gem 'database_cleaner'
gem 'launchy'
gem "capybara-webkit"
#gem 'rspec-multi-mock', :git => 'git://github.com/endeepak/rspec-multi-mock.git'
end
group :test do
#gem 'ruby-debug19', :require => 'ruby-debug'
end
gem 'execjs'
gem 'therubyracer'

Answer 1

First of all you have to delete Gemfile.lock
then update Gemfile to include rails 3.2.11
go to project directory
run bundle install
This may solve your problem