103 Installing Rails 4.2 LTS

Posted Over 4 years ago. Visible to the public.

This document describes how to swap out the official Rails 4.2 gems with Rails 4.2 LTS Show archive.org snapshot . If you have installed Rails LTS before and want to update to a newer version, please see our update instructions.


  1. Subscribe to a Rails LTS plan Show archive.org snapshot to receive your credentials. If you already have a paid subscription for another version of Rails LTS, you can use the same credentials for Rails 4.2 LTS at no additional cost.

  2. Make sure your project satisfies the system requirement for Rails LTS. This involves upgrading to the latest official Rails 4.2 release.

  3. Make sure that you have Bundler 1.10 or newer by running:

    gem list | grep bundler

    This should show you a line like this:

    bundler (1.10.6)

    If your version is lower than 1.10, you can update Bundler like this:

    gem install bundler

    Please note that you need to have a compatible version of Bundler on all PCs that will be running your application (developer boxes, production servers, staging servers).


  1. Open the Bundler configuration file (Gemfile) in your project's root directory and find this line:

    gem 'rails'

    Replace that line with the following code:

    source 'https://rubygems.org'
    source 'https://username:password@gems.railslts.com' do
      gem 'rails', '~> 4.2.10'
      gem 'actionmailer',     require: false
      gem 'actionpack',       require: false
      gem 'activemodel',      require: false
      gem 'activerecord',     require: false
      gem 'activesupport',    require: false
      gem 'railties',         require: false
      gem 'actionview',       require: false
      gem 'activejob',        require: false
      gem 'railslts-version', require: false
      gem 'rack',             require: false

    Replace username and password with your personal credentials that you received after subscribing to Rails LTS.
    Make sure a colon (:) separates username and password.

If you don't want these credentials in your Gemfile, you can either

  • set them in an environment variable BUNDLE_GEMS__RAILSLTS__COM=username:password.
  • use bundle config set gems.railslts.com username:password

In this case, just use source 'https://gems.railslts.com'.

Note that our repositories are available via SSL (https) only, http://... will not work.

  1. Run Bundler to complete the installation:

    bundle update rails

    You might get a lot of unrelated upgrades. If you want to get as few updates as necessary, you can instead try to use this:

    bundle update rails actionpack actionview actionmailer activemodel activerecord activesupport railties activejob --conservative
  2. Decide whether to enable optional security enhancements shipped with Rails LTS.

    In order to keep maximum compatibility to the official Ruby on Rails releases, Rails LTS disables all additional security features by default. We do however recommend the :hardened configuration, which includes improvements we believe to be reasonable defaults for increased security in most applications.

  3. Confirm that you are running the latest version of Rails 4.2 LTS.

  4. Follow your normal release process (run tests, push, deploy to staging, do smoke/whatever testing, deploy to production).

Congratulations! You successfully deployed your application using Rails LTS.

If you have chosen to subscribe to the Rails LTS Notification List when signing up, you will be notified whenever a new patch for Rails LTS becomes available.

Note on rails-ujs or jquery-ujs

See installation instructions here.

Breaking changes

  • By default, Rails LTS does not allow for strings to be used in polymorphic path helpers, e.g. url_for(['edit', @user]) is not allowed. Symbols are fine. You can opt out of this change
  • Mimicking Rails 5, Rails 4.2 LTS will try to use YAML.safe_load to deserialize certain database column. See details
Tobias Kraze
Last edit
2 months ago
Source code in this card is licensed under the MIT License.
Posted by Tobias Kraze to Rails LTS documentation (2018-09-28 12:44)