public/500.html
<!DOCTYPE html>
<html>
<head>
<meta charset='utf-8' />
<meta name='ROBOTS' content='NOODP' />
<title>We're sorry, but something went wrong (500)</title>
<link href='/assets/application.css' media='all' rel='stylesheet' type='text/css' />
</head>
<body>
<div class="dialog">
<h1>We're sorry, but something went wrong.</h1>
</div>
</body>
</html>