5 files changed, 42 insertions, 54 deletions
diff --git a/guides/code/getting_started/public/404.html b/guides/code/getting_started/public/404.html
index ae7b8649ae..3d287b135d 100644
--- a/guides/code/getting_started/public/404.html
+++ b/guides/code/getting_started/public/404.html
@@ -2,16 +2,15 @@
 <html>
 <head>
   <title>The page you were looking for doesn't exist (404)</title>
- <style>
-  body 
-  {
-    background-color: #efefef;
+  <style>
+  body {
+    background-color: #EFEFEF;
     color: #2E2F30;
     text-align: center;
-    font-family: arial,sans-serif;
+    font-family: arial, sans-serif;
   }
-  div.dialog
-  {
+
+  div.dialog {
     width: 25em;
     margin: 4em auto 0 auto;
     border: 1px solid #CCC;
@@ -24,17 +23,18 @@
     background-color: white;
     padding: 7px 4em 0 4em;
   }
-  h1{
+
+  h1 {
     font-size: 100%;
     color: #730E15;
     line-height: 1.5em;
   }
-  body>p
-  {
-    width: 33em; 
+
+  body > p {
+    width: 33em;
     margin: 0 auto 1em;
     padding: 1em 0;
-    background-color: #f7f7f7;
+    background-color: #F7F7F7;
     border: 1px solid #CCC;
     border-right-color: #999;
     border-bottom-color: #999;
@@ -42,7 +42,7 @@
     border-bottom-right-radius: 4px;
     border-top-color: #DADADA;
     color: #666;
-    box-shadow: 0 3px 8px rgba(50,50,50,0.17);
+    box-shadow: 0 3px 8px rgba(50, 50, 50, 0.17);
   }
   </style>
 </head>
diff --git a/guides/code/getting_started/public/422.html b/guides/code/getting_started/public/422.html
index 0b64eb4ae9..3b946bf4a4 100644
--- a/guides/code/getting_started/public/422.html
+++ b/guides/code/getting_started/public/422.html
@@ -2,16 +2,15 @@
 <html>
 <head>
   <title>The change you wanted was rejected (422)</title>
- <style>
-  body
-  {
-    background-color: #efefef;
+  <style>
+  body {
+    background-color: #EFEFEF;
     color: #2E2F30;
     text-align: center;
-    font-family: arial,sans-serif;
+    font-family: arial, sans-serif;
   }
-  div.dialog
-  {
+
+  div.dialog {
     width: 25em;
     margin: 4em auto 0 auto;
     border: 1px solid #CCC;
@@ -24,17 +23,18 @@
     background-color: white;
     padding: 7px 4em 0 4em;
   }
-  h1{
+
+  h1 {
     font-size: 100%;
     color: #730E15;
     line-height: 1.5em;
   }
-  body>p
-  {
+
+  body > p {
     width: 33em;
     margin: 0 auto 1em;
     padding: 1em 0;
-    background-color: #f7f7f7;
+    background-color: #F7F7F7;
     border: 1px solid #CCC;
     border-right-color: #999;
     border-bottom-color: #999;
@@ -42,7 +42,7 @@
     border-bottom-right-radius: 4px;
     border-top-color: #DADADA;
     color: #666;
-    box-shadow: 0 3px 8px rgba(50,50,50,0.17);
+    box-shadow: 0 3px 8px rgba(50, 50, 50, 0.17);
   }
   </style>
 </head>
diff --git a/guides/code/getting_started/public/500.html b/guides/code/getting_started/public/500.html
index 9641851e74..ccc4ad5656 100644
--- a/guides/code/getting_started/public/500.html
+++ b/guides/code/getting_started/public/500.html
@@ -2,16 +2,15 @@
 <html>
 <head>
   <title>We're sorry, but something went wrong (500)</title>
- <style>
-  body 
-  {
-    background-color: #efefef;
+  <style>
+  body {
+    background-color: #EFEFEF;
     color: #2E2F30;
     text-align: center;
-    font-family: arial,sans-serif;
+    font-family: arial, sans-serif;
   }
-  div.dialog
-  {
+
+  div.dialog {
     width: 25em;
     margin: 4em auto 0 auto;
     border: 1px solid #CCC;
@@ -24,17 +23,18 @@
     background-color: white;
     padding: 7px 4em 0 4em;
   }
-  h1{
+
+  h1 {
     font-size: 100%;
     color: #730E15;
     line-height: 1.5em;
   }
-  body>p
-  {
-    width: 33em; 
+
+  body > p {
+    width: 33em;
     margin: 0 auto 1em;
     padding: 1em 0;
-    background-color: #f7f7f7;
+    background-color: #F7F7F7;
     border: 1px solid #CCC;
     border-right-color: #999;
     border-bottom-color: #999;
@@ -42,7 +42,7 @@
     border-bottom-right-radius: 4px;
     border-top-color: #DADADA;
     color: #666;
-    box-shadow: 0 3px 8px rgba(50,50,50,0.17);
+    box-shadow: 0 3px 8px rgba(50, 50, 50, 0.17);
   }
   </style>
 </head>
diff --git a/guides/source/action_controller_overview.md b/guides/source/action_controller_overview.md
index 7e0a8a43d4..e01d0d57ea 100644
--- a/guides/source/action_controller_overview.md
+++ b/guides/source/action_controller_overview.md
@@ -194,7 +194,7 @@ class PeopleController < ActionController::Base
 
   # This will pass with flying colors as long as there's a person key
   # in the parameters, otherwise it'll raise a
-  # ActionController::MissingParameter exception, which will get
+  # ActionController::ParameterMissing exception, which will get
   # caught by ActionController::Base and turned into that 400 Bad
   # Request reply.
   def update
diff --git a/guides/source/upgrading_ruby_on_rails.md b/guides/source/upgrading_ruby_on_rails.md
index 0941bc7e58..af223873ec 100644
--- a/guides/source/upgrading_ruby_on_rails.md
+++ b/guides/source/upgrading_ruby_on_rails.md
@@ -103,32 +103,20 @@ Rails 4.0 extracted Active Resource to its own gem. If you still need the featur
 
 * Rails 4.0 changed how `assert_generates`, `assert_recognizes`, and `assert_routing` work. Now all these assertions raise `Assertion` instead of `ActionController::RoutingError`.
 
-* Rails 4.0 correctly prefers the first named route defined in `config/routes.rb` if a clashing route is found later. Check the output of `rake routes` before upgrading and remove unused named routes to avoid issues.
+* Rails 4.0 raises an `ArgumentError` if clashing named routes are defined. This can be triggered by explicitly defined named routes or by the `resources` method. Here are two examples that clash with routes named `example_path`:
 
 ```ruby
-  # config/routes.rb
   get 'one' => 'test#example', as: :example
   get 'two' => 'test#example', as: :example
-
-  # Rails 3
-  <%= example_path %> # => '/two'
-
-  # Rails 4
-  <%= example_path %> # => '/one'
 ```
 
 ```ruby
-  # config/routes.rb
   resources :examples
   get 'clashing/:id' => 'test#example', as: :example
-
-  # Rails 3
-  <%= example_path(1) %> # => '/clashing/1'
-
-  # Rails 4
-  <%= example_path(1) %> # => '/examples/1'
 ```
 
+In the first case, you can simply avoid using the same name for multiple routes. In the second, you can use the `only` or `except` options provided by the `resources` method to restrict the routes created as detailed in the [Routing Guide](http://guides.rubyonrails.org/routing.html#restricting-the-routes-created).
+
 * Rails 4.0 also changed the way unicode character routes are drawn. Now you can draw unicode character routes directly. If you already draw such routes, you must change them, for example:
 
 ```ruby