If you’re on an older version than 3.7 please follow previous upgrade guides and perform those upgrades incrementally**, eg.

  1. upgrade 3.4 to 3.5
  2. upgrade 3.5 to 3.6
  3. upgrade 3.6 to 3.7

Update your Ruby version to 2.5 or later

Spree 4.0 requires Ruby 2.5 so you need to change the ruby version in your project’s Gemfile and .ruby-version files. And of course you need to install Ruby 2.5 or later. If you’re using RVM you can do it like this:

rvm install 2.5
rvm use 2.5

Migrate from Paperclip to ActiveStorage

In Spree 3.6 we deprecated Paperclip support in favor of ActiveStorage. Paperclip gem itself isn’t maintained anymore and it is recommended to move to ActiveStorage as it is the default Rails storage engine since Rails 5.2 release.

In Spree 4.0 we’ve removed Paperclip support in favor of ActiveStorage.

Please remove also any occurrences of Rails.application.config.use_paperclip and Configuration::Paperclip from your codebase.

Please follow the official Paperclip to ActiveStorage migration guide.

Remove spree_address_book extension

If you’re using the Address Book extension you need to remove it as this feature was merged into core Spree.

  1. Remove this line from Gemfile

    bundle remove spree_address_book
    
  2. Remove this line from vendor/assets/javascripts/spree/frontend/all.js

     //= require spree/frontend/spree_address_book
    
  3. Remove this line from vendor/assets/stylesheets/spree/frontend/all.css

     //= require spree/frontend/spree_address_book
    

Update your Gemfile

gem 'spree', '~> 4.0'
gem 'spree_auth_devise', '~> 4.0'
gem 'spree_gateway', '~> 3.6'

and run

bundle update

Replace class_eval with Module.prepend only for Rails 6

Rails 6.0 ships with a new code autoloader called Zeitwerk which has some strict rules in terms of file naming and contents. If you used class_eval to extend and modify Spree classes you will need to rewrite those with Module.prepend. Eg.

Old decorator syntax:

Spree::Order.class_eval do
  has_many :new_custom_model

  def some_method
     # ...
  end
end

Replaced with:

module Spree
  module OrderDecorator
    def self.prepended(base)
      base.has_many :new_custom_model
    end

    def some_method
      # ...
    end
  end

  Order.prepend(OrderDecorator)
end

When migrating a class method to the new autoloader things are a little different because you will have to prepend to the Singleton class as shown in this example:

module Spree::BaseDecorator
  def spree_base_scopes
    # custom implementation
  end
end

Spree::Base.singleton_class.send :prepend, Spree::BaseDecorator

Please also consider other options for Logic Customization.

We recommend also reading through Ruby modules: Include vs Prepend vs Extend

Update Bootstrap 3 to 4 or stay at Bootstrap 3

Spree 4 uses Bootstrap 4 for both Storefront and Admin Panel. You have two options:

Stay at Bootstrap 3

As we know this is a big portion of work you can still use Bootstrap 3 for your Storefront.

  1. Copy all remaining views by running bundle exec spree:frontend:copy_views

  2. Add bootstrap-sass gem to your Gemfile

     gem 'bootstrap-sass', '~> 3.4.1'
    

Move to Bootstrap 4

Follow the official Bootstrap 3 to 4 migration guide

Install missing migrations

rake railties:install:migrations

Run migrations

rails db:migrate

Read the release notes

For information about changes contained within this release, please read the 4.0.0 Release Notes