PHP, MySQL - loginlogout issue, login only after second attempt

I have a very strange logout issue. The flow of the work: Log in page Main view (choosing a task) Task initialization that prepares the task in the background Task view (submitting some answer and clicking on submit) updates in the DB. initialization of the next line (go to number 3) I am using Session and cookies in order to login. The problem occurs only one time after logout the user tries to login. He succeffully reaches his Main view (different for each user) Successfully choose a task, go to the task view, enters submit. Then instead of the next page he receives "log out, please login" statement, meaning that my "checkUser" didnt find a session or a cookie and kicked him out. When he makes the login the next time, everything is working correctly. I dont understand where to begin to look for this issue. My login page relevant code: session_start(); $error_msg = ""; //Do you have Session or cookies? if (isset($_SESSION['user_id']) && isset( $_SESSION['user_role'])) { If ($_SESSION['user_role']=='DM') header('Location: DMView.php'); else if ($_SESSION['user_role']=='Vendor') header('Location: VendorView.php'); exit; } //If you dont - Did you enter sumbit? if (!isset($_SESSION['user_id']) && isset($_POST['submit'])) { // Grab the user-entered log-in data $user_username = mysqli_real_escape_string($con, trim($_POST['username'])); $user_password = mysqli_real_escape_string($con, trim($_POST['password'])); if (!empty($user_username) && !empty($user_password)) { // Look up the username and password in the database $query = "SELECT * FROM Users WHERE UserName = '$user_username' AND UserPassword = SHA('$user_password')"; $data = mysqli_query($con, $query); if (mysqli_num_rows($data) == 1) { // The log-in is OK so set the user ID and username session vars (and cookies), and redirect to the home page $row = mysqli_fetch_array($data); $_SESSION['user_id'] = $row['UserID']; $_SESSION['username'] = $row['UserName']; setcookie('user_id', $row['UserID'], time() + (60 * 60 * 24 * 30)); // expires in 30 days setcookie('username', $row['UserName'], time() + (60 * 60 * 24 * 30)); // expires in 30 days $user_role = $row['UserRole']; $_SESSION['user_role'] = $row['UserRole']; setcookie('user_role', $row['UserRole'], time() + (60 * 60 * 24 * 30)); // expires in 30 days $_SESSION['user_group'] = $row['UserGroup']; setcookie('user_group', $row['UserGroup'], time() + (60 * 60 * 24 * 30)); // expires in 30 days If ($user_role=='DM') header('Location: DMView.php'); else header('Location: VendorView.php'); } else { // The username/password are incorrect so set an error message $error_msg = 'Sorry, you must enter a valid username and password to log in.'; } } else { // The username/password weren't entered so set an error message $error_msg = 'Sorry, you must enter your username and password to log in.'; } } My checkUser file: if (session_status() == PHP_SESSION_NONE) { session_start(); } // If the session vars aren't set, try to set them with a cookie if (!isset($_SESSION['user_id'])) { if (isset($_COOKIE['user_id']) && isset($_COOKIE['username'])) { $_SESSION['user_id'] = $_COOKIE['user_id']; $_SESSION['username'] = $_COOKIE['username']; $_SESSION['user_role']=$_COOKIE['user_role']; $_SESSION['user_group'] = $_COOKIE['user_group']; } } if ((!isset($_SESSION['user_id'])) ) { echo '<p>Please <a href="index.php">log in</a> to access this page.</p>'; exit();} and my Logout file: // If the user is logged in, delete the session vars to log them out session_start(); if (isset($_SESSION['user_id'])) { // Delete the session vars by clearing the $_SESSION array $_SESSION = array(); // Delete the session cookie by setting its expiration to an hour ago (3600) if (isset($_COOKIE[session_name()])) { setcookie(session_name(), '', time() - 3600); } // Destroy the session session_destroy(); } // Delete the user ID and username cookies by setting their expirations to an hour ago (3600) setcookie('user_id', '', time() - 3600); setcookie('username', '', time() - 3600); // Redirect to the home page header('location: index.php'); The submit file (simplified with only one query): <?php require('connection.php'); require ('checkUser.php'); $task=$_POST['task_id']; $row=$_POST['row_id']; if( $_POST['answer']==1 ) { $query="UPDATE ecnmatchingdetails SET RowStatus=2,Agent='".$uName."' , VendorAnswer='Yes', VendorComment='".$_POST['comments']."' , end_tag='".date("Y-m-d H:i:s")."' where TaskID=".$task." and RowId=".$row; mysqli_query($con, $query); } else... } if( isset( $_POST['answer'])) { header( 'Location: http://dub-entas-124/tool/TT/WorkOnTask.php?id='.$task . '&start_task=0&prevID='.$Ebay_PRD_ID); exit(); } ?>