"Failed to open stream: Permission denied" Lighttpd on Ubuntu (VM Ware)

Question

The situation is, I have written some code in PHP to write JSON file in the server(Lighttpd) the code is

'''<?php

if ($_SERVER['REQUEST_METHOD'] == 'POST') {
    
    function get_data() {
        $datae = array();
        $datae[] = array(
            'Name' => $_POST['name'],
            'Branch' => $_POST['branch'],
            'Country' => $_POST['country'],
        );
        return json_encode($datae);
    }
    
    $name = "gfg";
    $file_name = $name . '.json';

    if(file_put_contents(
        "$file_name", get_data())) {
            echo $file_name .' file created';
            echo "<br><br><br><br><a href='get.html'>view data</a>";
        }
    else {
        echo 'There is some error';
    }
}

?> '''

this same code works fine with Apache servers. I have giver permissions as 777 to www folder

the error log of Lighttpd is 2022-10-13 09:50:13: (mod_fastcgi.c.451) FastCGI-stderr:PHP Warning: file_put_contents(gfg.json): Failed to open stream: Permission denied in /var/www/html/web/www/pc/a/gfg.php on line 18

any help will be appreciated