javascript - Failed to set session?

I used an image upload plug-in: uploadify. Due to the 302 error when uploading under IE and Firefox, I passed the current session name session_name() on the front end to the backend to re-establish the session, but I did the following, and the backend could I received the parameters of session_name(), but when I re-established the session, it failed. How to solve it?

Front desk:

<code>//这是uploadify插件向后端传送数据的参数
'formData'     : {
     'timestamp' : '<?php echo $timestamp;?>',
     'token'     : '<?php echo md5('unique_salt' . $timestamp);?>',
     '<?php echo session_name();?>' : '<?php echo session_id();?>',
     //上面的session参数渲染后是这样：'PHPSESSID':'',
            },</code>

Backend:

<code>//这是一个公共的控制器的初始化方法 里面验证登陆
function __construct() {
    parent::__construct();
    $session_name = session_name();  
    $post_session_name = $this->input->post($session_name);
    if (isset($post_session_name)) { //测试过  可以进入这里
        session_id($post_session_name);  //但是在这个地方好想设置会话失败
        session_start();
    }
    if ( !$this->session->valid_user() ){ //因为设置会话失败 这里通不过 前端返回302
        redirect( module_url( 'common/login' ) );
    }
}
</code>

Reply content:

I used an image upload plug-in: uploadify. Due to the 302 error when uploading under IE and Firefox, I passed the current session name session_name() on the front end to the backend to re-establish the session, but I did the following, and the backend could I received the parameters of session_name(), but when I re-established the session, it failed. How to solve it?

Front desk:

<code>//这是uploadify插件向后端传送数据的参数
'formData'     : {
     'timestamp' : '<?php echo $timestamp;?>',
     'token'     : '<?php echo md5('unique_salt' . $timestamp);?>',
     '<?php echo session_name();?>' : '<?php echo session_id();?>',
     //上面的session参数渲染后是这样：'PHPSESSID':'',
            },</code>

Backend:

<code>//这是一个公共的控制器的初始化方法 里面验证登陆
function __construct() {
    parent::__construct();
    $session_name = session_name();  
    $post_session_name = $this->input->post($session_name);
    if (isset($post_session_name)) { //测试过  可以进入这里
        session_id($post_session_name);  //但是在这个地方好想设置会话失败
        session_start();
    }
    if ( !$this->session->valid_user() ){ //因为设置会话失败 这里通不过 前端返回302
        redirect( module_url( 'common/login' ) );
    }
}
</code>

Check the log to see if there is any error message? session_id must be set before the session starts. Is the session already opened elsewhere before the __construct() call of this controller? Try adding session_abort() in front of the session_id line?

The default is to save session_id through cookie. Please check whether the cookie is disabled or cleared