HTML / PHP联系表单不适用于Heroku

Question

I've created a contact form on my website that worked using xampp server but it's not working on Heroku.

this is the HTML:

<form action="../php/contact.php" method="post">

            <div class="form-group">
                <label>Name</label>   
                <input type="text" name="name" class="form-control frame" required>
            </div>

            <div class="form-group">
                <label>email</label>
                <input type="email" name="email" class="form-control frame" required>
            </div>

            <br>

            <div class="form-group">
                <label>Message</label>    
                <textarea name="message" id="message" cols="" rows="" class="form-control frame"></textarea>
            </div>

            <br>

            <button class="btn btn-outline-secondary" type="submit" name="submit">Send</button>
</form>

And this is the PHP:

<?php
$name = $_POST['name'];
$visitorEmail = $_POST['email'];
$message = $_POST['message'];

$emailFrom = 'haizler.co.il';
$emailSubject = "New Form Submission";
$emailBody = "User Name: $name.
".
                "User Email: $visitorEmail.
".
                "User Message: $message.
";

$to = "[e-mail]";
$headers = "From: $emailFrom 
";
$headers .= "Replay-To: $visitorEmail 
";
mail($to,$emailSubject,$emailBody,$headers);
header("Location: contact.html");
?>

When filling the detail and clicking Send I get "Cannot POST /php/contact.php". I've tried changing the php address on the form action, and also tried putting the php file in the same folder has the html file but it didn't work.

This code worked using xampp (after changing the definitions on php.ini xampp file).

Thanks in advance!