10 files changed, 51 insertions, 23 deletions
diff --git a/guides/source/4_2_release_notes.md b/guides/source/4_2_release_notes.md
index a39dd9ace0..e8d1dc361a 100644
--- a/guides/source/4_2_release_notes.md
+++ b/guides/source/4_2_release_notes.md
@@ -94,6 +94,12 @@ Action Pack
 
 Please refer to the [Changelog][action-pack] for detailed changes.
 
+### Removals
+
+*   Removed deprecated `AbstractController::Helpers::ClassMethods::MissingHelperError`
+    in favor of `AbstractController::Helpers::MissingHelperError`.
+    ([Commit](https://github.com/rails/rails/commit/a1ddde15ae0d612ff2973de9cf768ed701b594e8))
+
 ### Deprecations
 
 *   Deprecated support for setting the `:to` option of a router to a symbol or a
diff --git a/guides/source/caching_with_rails.md b/guides/source/caching_with_rails.md
index 0902e347e2..d0f3a596fe 100644
--- a/guides/source/caching_with_rails.md
+++ b/guides/source/caching_with_rails.md
@@ -353,7 +353,12 @@ Instead of an options hash, you can also simply pass in a model, Rails will use
 class ProductsController < ApplicationController
   def show
     @product = Product.find(params[:id])
-    respond_with(@product) if stale?(@product)
+
+    if stale?(@product)
+      respond_to do |wants|
+        # ... normal response processing
+      end
+    end
   end
 end
 ```
diff --git a/guides/source/contributing_to_ruby_on_rails.md b/guides/source/contributing_to_ruby_on_rails.md
index 0b05725623..8bc4b10591 100644
--- a/guides/source/contributing_to_ruby_on_rails.md
+++ b/guides/source/contributing_to_ruby_on_rails.md
@@ -397,7 +397,7 @@ inside, just indent it with 4 spaces:
 
     class ArticlesController
       def index
-        respond_with Article.limit(10)
+        render json: Article.limit(10)
       end
     end
 
diff --git a/guides/source/engines.md b/guides/source/engines.md
index e9cce3f159..24548a5b01 100644
--- a/guides/source/engines.md
+++ b/guides/source/engines.md
@@ -136,7 +136,7 @@ following to the dummy application's routes file at
 `test/dummy/config/routes.rb`:
 
 ```ruby
-mount Blorgh::Engine, at: "blorgh"
+mount Blorgh::Engine => "/blorgh"
 ```
 
 ### Inside an Engine
@@ -173,7 +173,7 @@ Within `lib/blorgh/engine.rb` is the base class for the engine:
 
 ```ruby
 module Blorgh
-  class Engine < Rails::Engine
+  class Engine < ::Rails::Engine
     isolate_namespace Blorgh
   end
 end
diff --git a/guides/source/generators.md b/guides/source/generators.md
index 5e88fa0c70..2349908979 100644
--- a/guides/source/generators.md
+++ b/guides/source/generators.md
@@ -8,6 +8,7 @@ After reading this guide, you will know:
 * How to see which generators are available in your application.
 * How to create a generator using templates.
 * How Rails searches for generators before invoking them.
+* How Rails internally generates Rails code from the templates.
 * How to customize your scaffold by creating new generators.
 * How to customize your scaffold by changing generator templates.
 * How to use fallbacks to avoid overwriting a huge set of generators.
@@ -340,6 +341,20 @@ end
 
 If you generate another resource, you can see that we get exactly the same result! This is useful if you want to customize your scaffold templates and/or layout by just creating `edit.html.erb`, `index.html.erb` and so on inside `lib/templates/erb/scaffold`.
 
+Many scaffold templates in Rails are written in ERB tags which needs to be escaped, so that the output is a valid ERB code, that can be used correctly in Rails app.
+
+The following code in one of the generator file,
+
+```ruby
+<%%= stylesheet_include_tag :application %>
+```
+
+when passed through the generator, would generate the following output.
+
+```ruby
+<%= stylesheet_include_tag :application %>
+```
+
 Adding Generators Fallbacks
 ---------------------------
 
diff --git a/guides/source/layouts_and_rendering.md b/guides/source/layouts_and_rendering.md
index f00f7bca1b..8b37b92139 100644
--- a/guides/source/layouts_and_rendering.md
+++ b/guides/source/layouts_and_rendering.md
@@ -903,7 +903,7 @@ You can also specify multiple videos to play by passing an array of videos to th
 This will produce:
 
 ```erb
-<video><source src="trailer.ogg" /><source src="movie.ogg" /></video>
+<video><source src="/videos/trailer.ogg" /><source src="/videos/trailer.flv" /></video>
 ```
 
 #### Linking to Audio Files with the `audio_tag`
diff --git a/guides/source/plugins.md b/guides/source/plugins.md
index 489bd227cd..f10699fbeb 100644
--- a/guides/source/plugins.md
+++ b/guides/source/plugins.md
@@ -440,5 +440,5 @@ $ bin/rake rdoc
 
 * [Developing a RubyGem using Bundler](https://github.com/radar/guides/blob/master/gem-development.md)
 * [Using .gemspecs as Intended](http://yehudakatz.com/2010/04/02/using-gemspecs-as-intended/)
-* [Gemspec Reference](http://docs.rubygems.org/read/chapter/20)
+* [Gemspec Reference](http://guides.rubygems.org/specification-reference/)
 * [GemPlugins: A Brief Introduction to the Future of Rails Plugins](http://www.intridea.com/blog/2008/6/11/gemplugins-a-brief-introduction-to-the-future-of-rails-plugins)
diff --git a/guides/source/ruby_on_rails_guides_guidelines.md b/guides/source/ruby_on_rails_guides_guidelines.md
index f0230b428b..6206b3c715 100644
--- a/guides/source/ruby_on_rails_guides_guidelines.md
+++ b/guides/source/ruby_on_rails_guides_guidelines.md
@@ -13,17 +13,17 @@ After reading this guide, you will know:
 Markdown
 -------
 
-Guides are written in [GitHub Flavored Markdown](https://help.github.com/articles/github-flavored-markdown). There is comprehensive [documentation for Markdown](http://daringfireball.net/projects/markdown/syntax), a [cheatsheet](http://daringfireball.net/projects/markdown/basics).
+Guides are written in [GitHub Flavored Markdown](https://help.github.com/articles/github-flavored-markdown). There is comprehensive [documentation for Markdown](http://daringfireball.net/projects/markdown/syntax), as well as a [cheatsheet](http://daringfireball.net/projects/markdown/basics).
 
 Prologue
 --------
 
-Each guide should start with motivational text at the top (that's the little introduction in the blue area). The prologue should tell the reader what the guide is about, and what they will learn. See for example the [Routing Guide](routing.html).
+Each guide should start with motivational text at the top (that's the little introduction in the blue area). The prologue should tell the reader what the guide is about, and what they will learn. As an example, see the [Routing Guide](routing.html).
 
-Titles
+Headings
 ------
 
-The title of every guide uses `h1`; guide sections use `h2`; subsections `h3`; etc. However, the generated HTML output will have the heading tag starting from `<h2>`.
+The title of every guide uses an `h1` heading; guide sections use `h2` headings; subsections use `h3` headings; etc. Note that the generated HTML output will use heading tags starting with `<h2>`.
 
 ```
 Guide Title
@@ -35,14 +35,14 @@ Section
 ### Sub Section
 ```
 
-Capitalize all words except for internal articles, prepositions, conjunctions, and forms of the verb to be:
+When writing headings, capitalize all words except for prepositions, conjunctions, internal articles, and forms of the verb "to be":
 
 ```
 #### Middleware Stack is an Array
 #### When are Objects Saved?
 ```
 
-Use the same typography as in regular text:
+Use the same inline formatting as regular text:
 
 ```
 ##### The `:content_type` Option
@@ -51,25 +51,23 @@ Use the same typography as in regular text:
 API Documentation Guidelines
 ----------------------------
 
-The guides and the API should be coherent and consistent where appropriate. Please have a look at these particular sections of the [API Documentation Guidelines](api_documentation_guidelines.html):
+The guides and the API should be coherent and consistent where appropriate. In particular, these sections of the [API Documentation Guidelines](api_documentation_guidelines.html) also apply to the guides:
 
 * [Wording](api_documentation_guidelines.html#wording)
 * [Example Code](api_documentation_guidelines.html#example-code)
-* [Filenames](api_documentation_guidelines.html#filenames)
+* [Filenames](api_documentation_guidelines.html#file-names)
 * [Fonts](api_documentation_guidelines.html#fonts)
 
-Those guidelines apply also to guides.
-
 HTML Guides
 -----------
 
 Before generating the guides, make sure that you have the latest version of Bundler installed on your system. As of this writing, you must install Bundler 1.3.5 on your device.
 
-To install the latest version of Bundler, simply run the `gem install bundler` command
+To install the latest version of Bundler, run `gem install bundler`.
 
 ### Generation
 
-To generate all the guides, just `cd` into the `guides` directory, run `bundle install` and execute:
+To generate all the guides, just `cd` into the `guides` directory, run `bundle install`, and execute:
 
 ```
 bundle exec rake guides:generate
diff --git a/guides/source/security.md b/guides/source/security.md
index ebfcc5bdd0..125dd82666 100644
--- a/guides/source/security.md
+++ b/guides/source/security.md
@@ -118,9 +118,9 @@ It works like this:
 
 * A user receives credits, the amount is stored in a session (which is a bad idea anyway, but we'll do this for demonstration purposes).
 * The user buys something.
-* Their new, lower credit will be stored in the session.
-* The dark side of the user forces them to take the cookie from the first step (which they copied) and replace the current cookie in the browser.
-* The user has their credit back.
+* The new adjusted credit value is stored in the session.
+* The user takes the cookie from the first step (which they previously copied) and replaces the current cookie in the browser.
+* The user has their original credit back.
 
 Including a nonce (a random value) in the session solves replay attacks. A nonce is valid only once, and the server has to keep track of all the valid nonces. It gets even more complicated if you have several application servers (mongrels). Storing nonces in a database table would defeat the entire purpose of CookieStore (avoiding accessing the database).
 
@@ -847,7 +847,7 @@ It is recommended to _use RedCloth in combination with a whitelist input filter_
 
 NOTE: _The same security precautions have to be taken for Ajax actions as for "normal" ones. There is at least one exception, however: The output has to be escaped in the controller already, if the action doesn't render a view._
 
-If you use the [in_place_editor plugin](http://dev.rubyonrails.org/browser/plugins/in_place_editing), or actions that return a string, rather than rendering a view, _you have to escape the return value in the action_. Otherwise, if the return value contains a XSS string, the malicious code will be executed upon return to the browser. Escape any input value using the h() method.
+If you use the [in_place_editor plugin](https://rubygems.org/gems/in_place_editing), or actions that return a string, rather than rendering a view, _you have to escape the return value in the action_. Otherwise, if the return value contains a XSS string, the malicious code will be executed upon return to the browser. Escape any input value using the h() method.
 
 ### Command Line Injection
 
diff --git a/guides/source/upgrading_ruby_on_rails.md b/guides/source/upgrading_ruby_on_rails.md
index 62e4071935..cc20782780 100644
--- a/guides/source/upgrading_ruby_on_rails.md
+++ b/guides/source/upgrading_ruby_on_rails.md
@@ -54,7 +54,8 @@ NOTE: This section is a work in progress.
 
 ### Serialized attributes
 
-When assigning `nil` to a serialized attribute, it will be saved to the database
+When using a custom coder (e.g. `serialize :metadata, JSON`),
+assigning `nil` to a serialized attribute will save it to the database
 as `NULL` instead of passing the `nil` value through the coder (e.g. `"null"`
 when using the `JSON` coder).
 
@@ -624,6 +625,9 @@ Rails 4.0 no longer supports loading plugins from `vendor/plugins`. You must rep
 
 * Rails 4.0 has changed `serialized_attributes` and `attr_readonly` to class methods only. You shouldn't use instance methods since it's now deprecated. You should change them to use class methods, e.g. `self.serialized_attributes` to `self.class.serialized_attributes`.
 
+* When using the default coder, assigning `nil` to a serialized attribute will save it
+to the database as `NULL` instead of passing the `nil` value through YAML (`"--- \n...\n"`).
+
 * Rails 4.0 has removed `attr_accessible` and `attr_protected` feature in favor of Strong Parameters. You can use the [Protected Attributes gem](https://github.com/rails/protected_attributes) for a smooth upgrade path.
 
 * If you are not using Protected Attributes, you can remove any options related to