WordPress at a glance
filter is not described

graceful_fail_template filter-hook . WP 1.0

Usage

add_filter( 'graceful_fail_template', 'filter_function_name_67', 10, 2 );
function filter_function_name_67( $html, $html ){
	// filter...

	return $html;
}
$html
-
$html
-

Where the hook is called

graceful_fail()
wp-includes/ms-deprecated.php 92-115
$message_template = apply_filters( 'graceful_fail_template',
'<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml"><head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>Error!</title>
<style type="text/css">
img {
border: 0;
}
body {
line-height: 1.6em; font-family: Georgia, serif; width: 390px; margin: auto;
text-align: center;
}
.message {
font-size: 22px;
width: 350px;
margin: auto;
}
</style>
</head>
<body>
<p class="message">%s</p>
</body>
</html>' );

Where the hook is used (in WP core)

Does not used.