app/views/shared/access_denied.html.erb
<div id='access-denied'>
<h1> <%= @title || _('Access denied') %> </h1>
<% unless @message.nil? %>
<p><%= @message %></p>
<% else %>
<p><%= _('You are not allowed to view this page.') %></p>
<p><%= _("If you are supposed to have access to this area, you'll probably want to talk to the people responsible and ask them to give you access.") %></p>
<% end %>
<%= button_bar do %>
<%= button :back, _('Go back'), :back %>
<%= button :home, _('Go to the home page'), '/' %>
<% end %>
</div>