views/500.erb
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title><%= title 'Error 500' %></title>
<link href="<%= prefix_url("assets/application.css") %>" rel="stylesheet">
</head>
<body>
<div class="container-fluid">
<div class="row-fluid text-error service-page">
<h1>500 <small>Internal Server Error</small></h1>
<p class="lead">Sorry, something went wrong.</p>
<a href="/" class="btn btn-danger">Back to home</a>
</div>
</div>
</body>
</html>