app/views/layouts/error.html.erb
<!doctype html>
<html>
<head>
<meta charset="UTF-8" />
<title>Error!</title>
<style type="text/css">
<%= File.read(Gaffe.root.join('app/assets/stylesheets/errors.css')).gsub("\n", ' ').gsub(' ', ' ') %>
</style>
</head>
<body>
<div id="wrap">
<h1>Error!</h1>
<p>This is an error page brought to you by <a href="https://github.com/mirego/gaffe">Gaffe</a>.</p>
<div class="content">
<hr>
<%= yield %>
<hr>
</div>
<% if Rails.env.development? || Rails.env.test? %>
<p>Original exception (only displayed in <strong>development</strong> and <strong>test</strong> environment):</p>
<pre>
<code><%= @exception.inspect %></code>
</pre>
<% end %>
<p>You can overwrite this page by creating these files:</p>
<% handlers = ActionView::Template::Handlers.extensions.map(&:to_s).join(', ') %>
<pre>
<code><%= Rails.root.join('app', 'views', 'layouts', "error.html.<em title='#{handlers}'>handler</em>").to_s.html_safe %></code>
<code><%= Rails.root.join('app', 'views', 'errors', "#{@rescue_response.to_s}.html.<em title='#{handlers}'>handler</em>").to_s.html_safe %></code>
</pre>
</div>
</body>
</html>