I’m getting this file not found error when I go to localhost:3000 when I

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Asked: June 17, 20262026-06-17T07:55:06+00:00 2026-06-17T07:55:06+00:00

I’m getting this file not found error when I go to localhost:3000 when I

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I’m getting this file not found error when I go to localhost:3000 when I start running my rails server. The message I’m getting is couldn't find file 'jquery.effects.core'. I’ve pretty much done everything I can from pulling a new clone of the app from my repo to reinstalling Rails and Ruby, but it all leads to the same error. Any ideas?

I get the following output when I run my rails server:

sudo rails s
=> Booting Thin
=> Rails 3.2.9 application starting in development on http://0.0.0.0:3000
=> Call with -d to detach
=> Ctrl-C to shutdown server
        SECURITY WARNING: No secret option provided to Rack::Session::Cookie.
        This poses a security threat. It is strongly recommended that you
        provide a secret to prevent exploits that may be possible from crafted
        cookies. This will not be supported in future versions of Rack, and
        future versions will even invalidate your existing user cookies.

        Called from: /usr/local/rvm/rubies/ruby-1.9.2-p290/lib/ruby/gems/1.9.1/gems/actionpack-3.2.9/lib/action_dispatch/middleware/session/abstract_store.rb:28:in `initialize'.

>> Thin web server (v1.5.0 codename Knife)
>> Maximum connections set to 1024
>> Listening on 0.0.0.0:3000, CTRL+C to stop

and here’s my Gemfile

source 'https://rubygems.org'

gem 'rails', '3.2.9'

# Bundle edge Rails instead:
# gem 'rails', :git => 'git://github.com/rails/rails.git'

gem 'pg'
gem 'rails_admin'
gem 'devise'
gem 'cancan'
gem 'simple_form'
gem 'kaminari'
gem 'bootstrap-kaminari-views'
gem 'recaptcha', :require => 'recaptcha/rails'
gem 'acts_as_commentable_with_threading'

# Gems used only for assets and not required
# in production environments by default.
group :assets do
  gem 'sass-rails',   '~> 3.2.3'
  gem 'coffee-rails', '~> 3.2.1'
  gem 'uglifier', '>= 1.0.3'
end

group :production do
  gem 'thin'
end

gem 'libv8', '~> 3.11.8'
gem "therubyracer", '>= 0.11.0beta8', :require => 'v8'
gem 'twitter-bootstrap-rails', :git => 'git://github.com/seyhunak/twitter-bootstrap-rails.git'
gem "less-rails"

gem 'paperclip'
gem 'aws-sdk'

gem 'jquery-rails'

EDIT (Solved): Here’s my application.js file. Everything seems to work when I uncomment the = require jquery line. I don’t know how to explain this because there are others working with the same set of source code that don’t encounter this problem even though that line is commented out.

// This is a manifest file that'll be compiled into application.js, which will include all the files
// listed below.
//
// Any JavaScript/Coffee file within this directory, lib/assets/javascripts, vendor/assets/javascripts,
// or vendor/assets/javascripts of plugins, if any, can be referenced here using a relative path.
//
// It's not advisable to add code directly here, but if you do, it'll appear at the bottom of the
// the compiled file.
//
// WARNING: THE FIRST BLANK LINE MARKS THE END OF WHAT'S TO BE PROCESSED, ANY BLANK LINE SHOULD
// GO AFTER THE REQUIRES BELOW.
//
//= require jquery <----------------
//= require jquery_ujs
//= require twitter/bootstrap
//= require_tree .