What are the potential pitfalls of using Umlaute in links on Linux servers when developing in PHP?

Using Umlaute in links on Linux servers when developing in PHP can lead to encoding issues, as Linux servers typically use UTF-8 encoding while Umlaute characters are not always supported in this encoding. To avoid problems, it's recommended to encode Umlaute characters in URLs using urlencode() before including them in links.

$url = 'https://example.com/?param=' . urlencode('Umlaute: äöü');
echo '<a href="' . $url . '">Link</a>';