The header function is not working - php

Question

I created a signup form and once a user has successfully signed up, it should redirect to home.php. But instead, it's being redirected to index.php. Everything else works (please see the code below). I could see that a user was added to my database, and that the status of the profile picture is 1.
<?php
if (isset($_POST['submitSignup'])) {
include_once 'dbh.inc.php';
$first = $_POST['first'];
$last = $_POST['last'];
$email = $_POST['email'];
$username = $_POST['username'];
$password = $_POST['passwordS'];
if (empty($first) || empty($last) || empty($email) || empty($username) || empty($password)) {
header("Location: ../signup.php?signup=empty"); exit();}
else{
if (!preg_match("/^[A-Za-z\s'-]{2,50}$/", $first) || !preg_match("/^[A-Za-z\s'-]{2,50}$/", $last)) {
header("Location: ../signup.php?signup=flnameinvalid&email=$email&username=$username"); exit();}
else{
if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
header("Location: ../signup.php?signup=emailinvalid&first=$first&last=$last&username=$username"); exit();}
else{
$mysql = "SELECT * FROM users WHERE user_username='$username';";
$result = mysqli_query($conn, $mysql);
$resultCheck = mysqli_num_rows($result);
if ($resultCheck > 0) {
header("Location: ../signup.php?signup=unametaken&first=$first&last=$last&email=$email"); exit();}
else{
if (strlen($password) < 8) {
header("Location: ../signup.php?signup=strlen&first=$first&last=$last&email=$email&username=$username"); exit();}
else{
if (!preg_match("#[0-9]+#", $password)) {
header("Location: ../signup.php?signup=num&first=$first&last=$last&email=$email&username=$username"); exit();}
else{
if (!preg_match("#[A-Z]+#", $password)) {
header("Location: ../signup.php?signup=cap&first=$first&last=$last&email=$email&username=$username"); exit();}
else{
$hashedPwd = password_hash($password, PASSWORD_DEFAULT);
$sql = "INSERT INTO users (user_first, user_last, user_email, user_username, user_password)
VALUES (?, ?, ?, ?, ?);";
$stmt = mysqli_stmt_init($conn);
if (!mysqli_stmt_prepare ($stmt, $sql)) {
echo "SQL error!";}
else{
mysqli_stmt_bind_param ($stmt, "sssss", $first, $last, $email, $username, $hashedPwd);
mysqli_stmt_execute ($stmt);
$sql3 = "SELECT * FROM users WHERE user_username='$username' AND user_first='$first';";
$result = mysqli_query($conn, $sql3);
if (mysqli_num_rows($result) > 0) {
while ($row = mysqli_fetch_assoc($result)) {
$userid = $row['id'];
$sql4 = "INSERT INTO profileimg (userid, status) VALUES ($userid, 1);";
mysqli_query($conn, $sql4);
}
}
else{ echo "There are no users!";}
}
header("Location: ../home.php?signup=success"); exit();
}
}
}
}
}
}
}
}
else{header("Location: ../signup.php?signup=error");}
The header function doesn't work even if I placed it after the mysqli_execute($stmt).
I tried creating a user-defined function instead, but it is still not working.
It was working last night when I haven't added the last if and else statement yet, the one with $sql3.
========= UPDATED ==========
Somehow, I was able to identify that the redirect it is following is the header function within the last else statement of my home.php. Here's the code
<div class="sideright">
<?php
$sql = "SELECT * FROM users";
$result = mysqli_query($conn, $sql);
if (mysqli_num_rows($result) > 0) {
while ($row = mysqli_fetch_assoc($result)) {
$id = $row['id'];
$sqlImg = "SELECT * FROM profileimg where userid='$id'";
$resultImg = mysqli_query($conn, $sqlImg);
while ($rowImg = mysqli_fetch_assoc($resultImg)) {
echo "<div>";
if ($rowImg['status'] == 0) {
echo "<img src='uploads/profile".$id.".$fileActualExt'".mt_rand()." height='200' width='200'>";}
else{
echo "<img src='uploads/defaultprofilepicture.jpg' height='200' width='200'>";}
echo $row['user_username'];
echo "</div>";
}
}
}
else{
echo "Sorry, an error occurred.";}
if (isset($_SESSION['key'])) {
echo
'<form action="upload.php" method="POST" enctype="multipart/form-data">
<input type="file" name="file" value="Change Profile Picture">
<button type="submit" name="submitFile"> Go </button>
</form>';
echo
'<form action="includes/logout.inc.php" method="POST">
<button type="submit" name="submitLogout"> Log Out </button>
</form>';
}
else{
header("Location: index.php");}
I still haven't fixed it, please help me find out where I went wrong.

Answer 1

try
echo "<script type=\"text/javascript\">".
"window.location='signup.php?signup=error';".
"</script>";

Answer 2

You may try this, it's Working for me.
Replace this code to Your Header Location
<script type=\"text/javascript\">
window.location.href='home.php';
</script>