.php file opens as plain text when xampp is installed

Question

I have xampp installed on Windows 10 and i figured that when opening a php file it opens as plain text as bellow with the message "Something is wrong with the XAMPP installation :-(". I tried to uninstall and reinstall xampp but it didnt' work. Can somebody help please.

<?php
    if (!empty($_SERVER['HTTPS']) && ('on' == $_SERVER['HTTPS'])) {
        $uri = 'https://';
    } else {
        $uri = 'http://';
    }
    $uri .= $_SERVER['HTTP_HOST'];
    header('Location: '.$uri.'/dashboard/');
    exit;
?>

Something is wrong with the XAMPP installation :-(