Rails: Help with rake aborted error!

I have been trying to run the rake db:migrate command but it ain't working. I uninstalled and installed the gem but no luck. I read somewhere the o.9 wasn't stable and that 0.8.7 was ok. I tried it but I got an error also..

For now the error is

    Fayimora-Femi-Baloguns-MacBook-Pro:sample_app fayimora$ bundle exec rake db:migrate
    /Library/Ruby/Gems/1.8/gems/bundler-1.0.15/lib/bundler/runtime.rb:136: warning: Insecure     world writable dir /usr/local in PATH, mode 040777
/Library/Ruby/Gems/1.8/gems/bundler-1.0.15/lib/bundler/runtime.rb:136: warning: Insecure world writable dir /usr/local in PATH, mode 040777
(in /Users/fayimora/Sites/rails_projects/sample_app)
DEPRECATION WARNING: config.generators in Rails::Railtie is deprecated. Please use config.app_generators instead. (called from /Users/fayimora/Sites/rails_projects/sample_app/config/application.rb:12)
DEPRECATION WARNING: config.generators in Rails::Railtie is deprecated. Please use config.app_generators instead. (called from /Users/fayimora/Sites/rails_projects/sample_app/config/application.rb:12)
rake aborted!
undefined method `prerequisites' for nil:NilClass
/Users/fayimora/Sites/rails_projects/sample_app/Rakefile:7
(See full trace by running task with --trace)

My gem list is

Fayimora-Femi-Baloguns-MacBook-Pro:sample_app fayimora$ bundle
Using rake (0.8.7) 
Using ZenTest (4.5.0) 
Using multi_json (1.0.3) 
Using activesupport (3.1.0.rc4) 
Using bcrypt-ruby (2.1.4) 
Using builder (3.0.0) 
Using i18n (0.6.0) 
Using activemodel (3.1.0.rc4) 
Using erubis (2.7.0) 
Using rack (1.3.1) 
Using rack-cache (1.0.2) 
Using rack-mount (0.8.1) 
Using rack-test (0.6.0) 
Using hike (1.1.0) 
Using tilt (1.3.2) 
Using sprockets (2.0.0.beta.10) 
Using tzinfo (0.3.29) 
Using actionpack (3.1.0.rc4) 
Using mime-types (1.16) 
Using polyglot (0.3.1) 
Using treetop (1.4.9) 
Using mail (2.3.0) 
Using actionmailer (3.1.0.rc4) 
Using arel (2.1.3) 
Using activerecord (3.1.0.rc4) 
Using activeresource (3.1.0.rc4) 
Using autotest (4.4.6) 
Using sys-uname (0.8.5) 
Using autotest-fsevent (0.2.4) 
Using autotest-growl (0.2.9) 
Using autotest-rails-pure (4.1.2) 
Using b开发者_JS百科undler (1.0.15) 
Using coffee-script-source (1.1.1) 
Using execjs (1.2.0) 
Using coffee-script (2.2.0) 
Using diff-lcs (1.1.2) 
Using rack-ssl (1.3.2) 
Using rdoc (3.8) 
Using thor (0.14.6) 
Using railties (3.1.0.rc4) 
Using jquery-rails (1.0.12) 
Using json (1.5.3) 
Using nokogiri (1.5.0) 
Using rails (3.1.0.rc4) 
Using rspec-core (2.0.0.beta.18) 
Using rspec-expectations (2.0.0.beta.18) 
Using rspec-mocks (2.0.0.beta.18) 
Using rspec (2.0.0.beta.18) 
Using webrat (0.7.3) 
Using rspec-rails (2.0.0.beta.18) 
Using sass (3.1.4) 
Using sass-rails (3.1.0.rc.4) 
Using spork (0.9.0.rc8) 
Using sqlite3 (1.3.3) 
Using uglifier (1.0.0) 

Contents of Rakefile

#!/usr/bin/env rake
# Add your own tasks in files placed in lib/tasks ending in .rake,
# for example lib/tasks/capistrano.rake, and they will automatically be available to Rake.
# require 'rake/dsl_definition'
require File.expand_path('../config/application', __FILE__)

SampleApp::Application.load_tasks

Please any help would be apprecible. Been having a real hard time learning rails.

The bug with Rake 0.9.2 is fixed. Try using Rake 0.9.2 by adding it to your Gemfile and run

bundle update rake.

I wouldn't use Rails 3.1 RCs besides experimenting or checking your gems for compatibility. Rails 3.0.9 is pretty stable and widely supported.

Edit: https://github.com/rails/rails/issues/1197

The problem is related to a gem not being compatible with Rails 3.1. Try to remove rspec from your Gemfile, bundle install, and run your rake tasks.