Php 取消定义索引：会话错误

每当有人登录

$\u会话['semail']和
$\u会话['username2']
。每当我进入profile页面时，我都会将session设置为一个变量，比如
$email=$\u session['semail']
然后在错误日志中，错误记录为：

Undefined index: semail in /home/twekr/public_html/profile.php on line 11

我的会话从页面顶部开始，如下所示：

session_name('twekr');
session_start();
ob_start();

下面是脚本中创建错误的一小部分：

 <?php 
 session_name('twekr');
 session_start();
 ob_start();
 if(!isset($_SESSION['semail']))
 {
 header("Location:https://www.twekr.com/");
 }
 if(isset($_GET['user']))
 {
 $id = $_GET['user'];
 $user = $_SESSION['semail'];
 $userid1 = $_SESSION['username2']; 
 include_once('config/db.php');
 include_once('frnds/functions.php');
 require('config/dbsettings.php');
 $userquery= "SELECT * FROM users WHERE email='$user'";
 $userquery=$sp->query($userquery) or die($sp->error);
 $info=$userquery->fetch_object();
 $userr = $info->username;

$get
在下面执行：

 $check_login = mysqli_query($con, "SELECT username FROM users WHERE  
 email ='$uemail' AND password ='$upass'");
 if(mysqli_num_rows($check_login) ==1) {

     $get = mysqli_fetch_array($check_login);
   $_SESSION['username2'] = $get['username'];

$get来自用户数据库。。。我已经更新了问题
$user=$\u SESSION['semail']-
$\u会话['semail']=$uemail非常仔细地查看这两个。同样适用于
其中email='$user'
那么我该怎么办@Fred ii使用相同的变量。仍然存在相同的错误@Fred ii-
 $check_login = mysqli_query($con, "SELECT username FROM users WHERE  
 email ='$uemail' AND password ='$upass'");
 if(mysqli_num_rows($check_login) ==1) {

     $get = mysqli_fetch_array($check_login);
   $_SESSION['username2'] = $get['username'];