redmine/app/views/common/error.html.erb

<h2><%= @status %></h2>

<% if @message.present? %>
  <p id="errorExplanation"><%= @message %></p>
<% end %>

<% if @archived_project && User.current.admin? %>
  <p><%= link_to l(:button_unarchive), unarchive_project_path(@archived_project), :method => :post, :class => 'icon icon-unlock' %></p>
<% end %>

<p><a href="javascript:history.back()"><%= l(:button_back) %></a></p>

<% html_title @status %>