Index not found error

Hello,

w3tc version 0.9.5.2

In my cron email report I receive this

Notice: Trying to get property of non-object in /home/mysite/public_html/wp-content/plugins/w3-total-cache/PgCache_Flush.php on line 62

Notice: Trying to get property of non-object in /home/mysite/public_html/wp-content/plugins/w3-total-cache/PgCache_Flush.php on line 62

Notice: Undefined index: SERVER_PROTOCOL in /home/mysite/public_html/wp-includes/load.php on line 16

I just opened the load.php and the mentione row is part of this function

function wp_get_server_protocol() {
	$protocol = $_SERVER['SERVER_PROTOCOL'];
	if ( ! in_array( $protocol, array( 'HTTP/1.1', 'HTTP/2', 'HTTP/2.0' ) ) ) {
		$protocol = 'HTTP/1.0';
	}
	return $protocol;
}

any ideas what can be wrong?

Thanks!