PHP7会话不保存,即使PHPSESSID相同

让我感到奇怪的是,“PHPSESSID”没有改变,所以会话已经设置好了。

当我删除cookie并刷新页面时,“PHPSESSID”会发生变化。

这是我的代码:

if (!is_writable(session_save_path())) {
    echo 'Session path "'.session_save_path().'" is not writable for PHP!';
} // checking if its the problem but it's not. 

if (!isset($_SESSION['started'])) { 
// i've tried with session_status() == PHP_SESSION_NONE but with the 
// same result
    session_start();
    echo 'session started<br>';
    $_SESSION['started'] = 1;
    $_SESSION['test']= 'TestValue<br>';
}

echo ($_SESSION['test']) ?? 'Nothing Found<br>';

输出总是:

session started
TestValue

PHP版本:7.1.13

系统:Ubuntu 16.04