Error 520

Thank you for your reply. I don’t seem to be able to access the Admin page of my WordPress, would there be any way to deactivate it without accessing the admin?

Also, is there any error you may see (or file that I may send you) for you to check what is causing the issue?

Many thanks in advance once again for your prompt reply.

The advanced cache file looks like this:

<?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;
	$robots_request = strpos( $_SERVER['REQUEST_URI'], 'robots.txt' ) != false;

	$skip_output = ( $doing_ajax || $xmlrpc_request || $rest_request || $robots_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' );
}

Tried and had this error instead

[09-Jun-2019 11:32:10 UTC] PHP Warning: strpos(): Empty needle in /web/htdocs/www.aliceceramica.com/home/wp-includes/plugin.php on line 658

Odd situation all of a sudden. I should perhaps write the Super Cache guys too.

In the meantime thanks once again for your help and patience.

For some mysterious reason I switched the Cloudfare icon from orange to grey on the website DNS and it worked!