How can PHP developers effectively debug and troubleshoot issues related to form submissions and action recognition in their code?

To effectively debug and troubleshoot form submission and action recognition issues in PHP, developers can start by checking if the form method matches the PHP code handling the submission, ensuring that form fields are correctly named and accessible in the PHP code, and using var_dump or print_r to inspect the $_POST or $_GET arrays for submitted data.

<form method="post" action="process_form.php">
    <input type="text" name="username">
    <input type="password" name="password">
    <button type="submit">Submit</button>
</form>
```

```php
<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $username = $_POST['username'];
    $password = $_POST['password'];
    
    // Process form data here
}
?>