更换服务器后网站后台出现空白，经研究发现这个函数在PHP5.4版本中已经被弃用了，已经被删除了。也就是这个函数不再可用了。直接注释掉就可以了，不用进行注册就可以声明session。

解决方法是：

找到include文件夹中的userlogin.class.php文件中

@session_register下的所有语句屏蔽掉。红色部分

function keepUser()
{
if($this->userID != ” && $this->userType != ”)
{
global $admincachefile,$adminstyle;
if(empty($adminstyle)) $adminstyle = ‘dedecms’;

/*@session_register($this->keepUserIDTag);*/
$_SESSION[$this->keepUserIDTag] = $this->userID;

/* @session_register($this->keepUserTypeTag);*/
$_SESSION[$this->keepUserTypeTag] = $this->userType;

/* @session_register($this->keepUserChannelTag);*/
$_SESSION[$this->keepUserChannelTag] = $this->userChannel;

/*@session_register($this->keepUserNameTag);*/
$_SESSION[$this->keepUserNameTag] = $this->userName;

/* @session_register($this->keepUserPurviewTag);*/
$_SESSION[$this->keepUserPurviewTag] = $this->userPurview;

/*@session_register($this->keepAdminStyleTag);*/
$_SESSION[$this->keepAdminStyleTag] = $adminstyle;

PutCookie(‘DedeUserID’, $this->userID, 3600 * 24, ‘/’);
PutCookie(‘DedeLoginTime’, time(), 3600 * 24, ‘/’);

$this->ReWriteAdminChannel();

return 1;
}
else{….以下省略