What could be causing the "Wie möchten Sie mit .php verfahren" message to appear after submitting a registration form in PHP?

The message "Wie möchten Sie mit .php verfahren" is likely appearing after submitting a registration form in PHP because the form action is set to a PHP file that is not handling the form submission correctly. To solve this issue, ensure that the form action points to the correct PHP file that processes the form data and redirects the user to the appropriate page after submission.

<!-- HTML form code -->
<form action="process_form.php" method="post">
  <!-- Form fields -->
</form>
```

In the "process_form.php" file, handle the form submission and redirect the user to the desired page:

```php
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
  // Process form data here
  
  // Redirect user to a success page
  header("Location: success_page.php");
  exit();
}
?>