i am try to create session but always session empty - php

Question

I want to try to make a session but always session Empty.Use this code rate this product this link send an email open email and click link Active than code working session empty please help me...
<?php
session_start();
include("myhomeportal/setting/config.php");
$conform = $_GET['conform'];
$query = mysqli_query($conn, "SELECT * FROM item_users where com_code='$conform'");
$row = mysqli_fetch_array($query);
if ($row) {
// now update `com_code`
$sql = "UPDATE item_users SET com_code='active', user_type='user' WHERE com_code='$conform'";
$result = mysqli_query($conn, $sql) or die(mysqli_error());
$inventory_id = $row['inventory_id'];
$active = $row['com_code'];
$_SESSION['sess_active'] = $active;
header("Location: category.php?inventory_id=$inventory_id");
} else {
// confirm code not found, show error
}
?>

Answer 1

Try to debug first.
Echo this $row['com_code']; then $_SESSION['sess_active'].
If they print something then go ahead.

Answer 2

There ir an error in your test page.
"sir other page is not working session just simple test code – Pankaj"
Instead you are only testing, you must start the session always with session_start() in every .php you want to use session.
Solving testing page.
"<h1>welcome <?php session_start(); echo $_SESSION['sess_active'];?> </h1> – Panka"
Note from w3schools:
The session_start() function must be the very first thing in your document. Before any HTML tags.
you are writting some html code before start the session, you should do that way:
<? php session_start(); ?>
<h1>welcome <?= $_SESSION['sess_active']; ?> </h1>
You can read more about this https://www.w3schools.com/php/php_sessions.asp