borospohar

I have made a log in form for my project. The error message is being displayed when I'm on localhost, but it does not show up when I upload it to the server, instead the page refreshes when Log in button gets clicked. What am I doing wrong? Here is the source: //This is the logic. This passes the data to the auth.php page (see code below) <?php require 'database.php'; require 'constants.php'; if (isset($_POST['username']) && isset($_POST['password'])) { function validate($con){ $con = trim($con); $con = stripslashes($con); $con = htmlspecialchars($con); return $con; } $username = validate($_POST['username']); $pass = validate($_POST['password']); //If username/password field is empty -> error message if (empty($username)) { header("Location: " . ROOT_URL . "auth.php?error=Username is needed"); exit(); }else if(empty($pass)){ header("Location: " . ROOT_URL . "auth.php?error=Password is needed"); exit(); }else{ $result = $con->query("SELECT * FROM users WHERE username='$username' AND password='$pass'"); //If username/password fields are correct/wrong -> move to index page/error message if ($result->num_rows === 1) { $row = $result->fetch_assoc(); if ($row['username'] === $username && $row['password'] === $pass) { $_SESSION['username'] = $row['username']; header("Location: " . ROOT_URL); exit(); }else{ header("Location: " . ROOT_URL . "auth.php?error=Wrong username or password!"); exit(); } }else{ header("Location: " . ROOT_URL . "auth.php?error=Wrong username or password!"); exit(); } } }else{ header("Location: " . ROOT_URL . "auth.php"); exit(); } Here is frontend part with the error feedback: <?php //Getting the database informations require 'config/database.php'; ?> //Getting the information from the code above shown <form action="success-auth.php" method="POST"> <!-- <?= ROOT_URL ?> --> <header> <div class="main-header"> //The error message, which only works in localhost <?php if (isset($_GET['error'])) { ?> <p class="alert__message error"><?php echo $_GET['error']; ?></p> <?php } ?> <div class="inp"> <input type="text" name="username" placeholder="Username"> </div> <div class="inp"> <input type="password" id="btn" name="password" placeholder="Password"> </div> <p><button type="submit" name="submit">Log in</button></p> </div> </header> </form> I can't find what the issue is. Any kind of help is appreciated!