advanced-cache.php

<?php
# WP SUPER CACHE 1.2
function wpcache_broken_message() {
	global $wp_cache_config_file;
	if ( isset( $wp_cache_config_file ) == false )
		return '';

	$doing_ajax =     defined( 'DOING_AJAX' ) && DOING_AJAX;
	$xmlrpc_request = defined( 'XMLRPC_REQUEST' ) && XMLRPC_REQUEST;
	$rest_request =   defined( 'REST_REQUEST' ) && REST_REQUEST;

	$skip_output = ( $doing_ajax || $xmlrpc_request || $rest_request );
	if ( false == strpos( $_SERVER[ 'REQUEST_URI' ], 'wp-admin' ) && !$skip_output ) {
		echo "<!-- WP Super Cache is installed but broken. The constant WPCACHEHOME must be set in the file wp-config.php and point at the WP Super Cache plugin directory. -->";
	}
}

if ( false == defined( 'WPCACHEHOME' ) ) {
	define( 'ADVANCEDCACHEPROBLEM', 1 );
} elseif ( !include_once( WPCACHEHOME . 'wp-cache-phase1.php' ) ) {
	if ( !@is_file( WPCACHEHOME . 'wp-cache-phase1.php' ) ) {
		define( 'ADVANCEDCACHEPROBLEM', 1 );
	}
}
if ( defined( 'ADVANCEDCACHEPROBLEM' ) )
	register_shutdown_function( 'wpcache_broken_message' );
?>