WordPress at a glance
function is not described

_default_wp_die_handler() WP 3.0.0

Kills WordPress execution and displays HTML page with an error message.

This is the default handler for wp_die(). If you want a custom one, you can override this using the 'wp_die_handler' filter in wp_die().

No Hooks.

Return

Nothing (null).

Usage

_default_wp_die_handler( $message, $title, $args );
$message(string/WP_Error) (required)
Error message or WP_Error object.
$title(string)
Error title.
Default: ''
$args(string/array)
Arguments to control behavior.
Default: empty array

Code of default wp die handler: wp-includes/functions.php WP 5.2

<?php
function _default_wp_die_handler( $message, $title = '', $args = array() ) {
	list( $message, $title, $r ) = _wp_die_process_input( $message, $title, $args );

	if ( is_string( $message ) ) {
		if ( ! empty( $r['additional_errors'] ) ) {
			$message = array_merge(
				array( $message ),
				wp_list_pluck( $r['additional_errors'], 'message' )
			);
			$message = "<ul>\n\t\t<li>" . join( "</li>\n\t\t<li>", $message ) . "</li>\n\t</ul>";
		} else {
			$message = "<p>$message</p>";
		}
	}

	$have_gettext = function_exists( '__' );

	if ( ! empty( $r['link_url'] ) && ! empty( $r['link_text'] ) ) {
		$link_url = $r['link_url'];
		if ( function_exists( 'esc_url' ) ) {
			$link_url = esc_url( $link_url );
		}
		$link_text = $r['link_text'];
		$message  .= "\n<p><a href='{$link_url}'>{$link_text}</a></p>";
	}

	if ( isset( $r['back_link'] ) && $r['back_link'] ) {
		$back_text = $have_gettext ? __( '&laquo; Back' ) : '&laquo; Back';
		$message  .= "\n<p><a href='javascript:history.back()'>$back_text</a></p>";
	}

	if ( ! did_action( 'admin_head' ) ) :
		if ( ! headers_sent() ) {
			header( 'Content-Type: text/html; charset=utf-8' );
			status_header( $r['response'] );
			nocache_headers();
		}

		$text_direction = $r['text_direction'];
		if ( function_exists( 'language_attributes' ) && function_exists( 'is_rtl' ) ) {
			$dir_attr = get_language_attributes();
		} else {
			$dir_attr = "dir='$text_direction'";
		}
		?>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml" <?php echo $dir_attr; ?>>
<head>
	<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
	<meta name="viewport" content="width=device-width">
		<?php
		if ( function_exists( 'wp_no_robots' ) ) {
			wp_no_robots();
		}
		?>
	<title><?php echo $title; ?></title>
	<style type="text/css">
		html {
			background: #f1f1f1;
		}
		body {
			background: #fff;
			color: #444;
			font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen-Sans, Ubuntu, Cantarell, "Helvetica Neue", sans-serif;
			margin: 2em auto;
			padding: 1em 2em;
			max-width: 700px;
			-webkit-box-shadow: 0 1px 3px rgba(0, 0, 0, 0.13);
			box-shadow: 0 1px 3px rgba(0, 0, 0, 0.13);
		}
		h1 {
			border-bottom: 1px solid #dadada;
			clear: both;
			color: #666;
			font-size: 24px;
			margin: 30px 0 0 0;
			padding: 0;
			padding-bottom: 7px;
		}
		#error-page {
			margin-top: 50px;
		}
		#error-page p {
			font-size: 14px;
			line-height: 1.5;
			margin: 25px 0 20px;
		}
		#error-page code {
			font-family: Consolas, Monaco, monospace;
		}
		ul li {
			margin-bottom: 10px;
			font-size: 14px ;
		}
		a {
			color: #0073aa;
		}
		a:hover,
		a:active {
			color: #00a0d2;
		}
		a:focus {
			color: #124964;
			-webkit-box-shadow:
				0 0 0 1px #5b9dd9,
				0 0 2px 1px rgba(30, 140, 190, 0.8);
			box-shadow:
				0 0 0 1px #5b9dd9,
				0 0 2px 1px rgba(30, 140, 190, 0.8);
			outline: none;
		}
		.button {
			background: #f7f7f7;
			border: 1px solid #ccc;
			color: #555;
			display: inline-block;
			text-decoration: none;
			font-size: 13px;
			line-height: 26px;
			height: 28px;
			margin: 0;
			padding: 0 10px 1px;
			cursor: pointer;
			-webkit-border-radius: 3px;
			-webkit-appearance: none;
			border-radius: 3px;
			white-space: nowrap;
			-webkit-box-sizing: border-box;
			-moz-box-sizing:    border-box;
			box-sizing:         border-box;

			-webkit-box-shadow: 0 1px 0 #ccc;
			box-shadow: 0 1px 0 #ccc;
			 vertical-align: top;
		}

		.button.button-large {
			height: 30px;
			line-height: 28px;
			padding: 0 12px 2px;
		}

		.button:hover,
		.button:focus {
			background: #fafafa;
			border-color: #999;
			color: #23282d;
		}

		.button:focus {
			border-color: #5b9dd9;
			-webkit-box-shadow: 0 0 3px rgba(0, 115, 170, 0.8);
			box-shadow: 0 0 3px rgba(0, 115, 170, 0.8);
			outline: none;
		}

		.button:active {
			background: #eee;
			border-color: #999;
			 -webkit-box-shadow: inset 0 2px 5px -3px rgba(0, 0, 0, 0.5);
			 box-shadow: inset 0 2px 5px -3px rgba(0, 0, 0, 0.5);
			 -webkit-transform: translateY(1px);
			 -ms-transform: translateY(1px);
			 transform: translateY(1px);
		}

		<?php
		if ( 'rtl' == $text_direction ) {
			echo 'body { font-family: Tahoma, Arial; }';
		}
		?>
	</style>
</head>
<body id="error-page">
<?php endif; // ! did_action( 'admin_head' ) ?>
	<?php echo $message; ?>
</body>
</html>
	<?php
	if ( $r['exit'] ) {
		die();
	}
}