PHP头重定向适用于Apache，但不适用于Nginx

Question

I have a contact form that will resubmit data if you refresh the page, so I added header("Location: http://www.example.com/form.php"); at the end of it so the page redirects back to itself and ultimately resets the form, preventing it from being submitted multiple times. It works exactly how I want it to on my local Apache server, but when I use the same code on an Nginx server, the form stops working altogether. Removing header("Location: http://www.example.com/form.php"); allows the form to work on the Nginx server, but then I will still have the resubmitting issue.

Is there a way to get header redirects to work with Nginx? If not, is there an alternative way to prevent my form from being resubmitted when people refresh the page?

Note: I tried adding header("HTTP/1.0 301 Moved Permanently"); on the line above header("Location: http://www.example.com/form.php");, as that was a possible solution I found, but it didn't solve anything.

EDIT: I put example.com in my post as I didn't want to put the real URL I am redirecting to.

Here is some code:

 <?php
        // define variables and set to empty values
        $firstnameErr = $lastnameErr = $emailErr = $companyErr = "";
        $firstname = $lastname = $email = $company = $comments = "";


        if ($_SERVER["REQUEST_METHOD"] == "POST") {
            $error = false;
            //Verifying first name input
            if (empty($_POST["firstname"])) {
                $firstnameErr = "First name is required";
                $error = true;
            } else {
                $firstname = test_input($_POST["firstname"]);
                // Check if first name only contains letters and whitespace
                if (!preg_match("/^[a-zA-Z ]*$/", $firstname)) {
                    $firstnameErr = "Only letters and white space allowed";
                    $error = true;
                }

            }

            //Verifying last name input
            if (empty($_POST["lastname"])) {
                $lastnameErr = "Last name is required";
                $error = true;
            } else {
                $lastname = test_input($_POST["lastname"]);
                // Check if last name only contains letters and whitespace
                if (!preg_match("/^[a-zA-Z ]*$/", $lastname)) {
                    $lastnameErr = "Only letters and white space allowed";
                    $error = true;
                }
            }

            //Verifying email input
            if (empty($_POST["email"])) {
                $emailErr = "Email is required";
                $error = true;
            } else {
                $email = test_input($_POST["email"]);
                // Check if email is well-formed
                if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
                    $emailErr = "Invalid email format";
                    $error = true;
                }
            }

            //Verifying company input
            if (empty($_POST["company"])) {
                $companyErr = "Company name is required";
                $error = true;
            } else {
                $company = test_input($_POST["company"]);
            }

            //Verifying comments input (empty input is allowed)
            if (empty($_POST["comments"])) {
                $comments = "";
            } else {
                $comments = test_input($_POST["comments"]);
            }

            if (!$error){
            // Email sent to me
            mail("[e-mail]", "Email subject", "Email message");
            // Confirmation email to potential client
            mail("[e-mail]", "Email subject", "Email message");
            }
            // Loads new, empty form (otherwise refreshing page will resubmit form)
            header("HTTP/1.0 301 Moved Permanently");
            header("Location: http://www.example.com/request.php");
        }


        function test_input($data) {
            $data = trim($data);
            $data = stripslashes($data);
            $data = htmlspecialchars($data);
            return $data;
        }
      ?>


 <form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>" method="post">
    <label>Name*</label>
    <input type="text" name="firstname" placeholder="First" size="20">
    <span class="error"><?php echo $firstnameErr;?></span>
    <input type="text" name="lastname" placeholder="Last" size="20" class="form-control">
    <span class="error"><?php echo $lastnameErr;?></span>
    <label>Email*</label>
    <input type="text" name="email" placeholder="Email" size="50" class="form-control">
    <span class="error"><?php echo $emailErr;?></span>
    <label>Company*</label>
    <input type="text" name="company" placeholder="Company" size="50" class="form-control">
    <span class="error"><?php echo $companyErr;?></span>
    <label>Comments</label>
    <textarea rows="4" name="comments" placeholder="Comments..." class="form-control"></textarea>
    <br>
    <input type="submit" value="Submit" class="submit-btn">
</form>

Answer 1

header('Status: 301 Moved Permanently', false, 301);    
header('Location: http://www.thedigideck.com/request.php');    
exit();      

Or just use this redirect function

function redirect($url) {
  $content = sprintf('<!DOCTYPE html>
  <html>
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="refresh" content="1;url=%1$s" />

    <title>Redirecting to %1$s</title>
  </head>
  <body>
    Redirecting to <a href="%1$s">%1$s</a>.
  </body>
  </html>', htmlspecialchars($url, ENT_QUOTES, 'UTF-8'));

  header('Location: ' . $url);

  die($content);
}

So it sets redirect header and returns body with redirect if the header didn't work.