What are some common issues when using the PHP header function for redirection, and how can they be resolved?

One common issue when using the PHP header function for redirection is that it must be called before any output is sent to the browser. To resolve this, ensure that there is no whitespace or HTML tags before the header function is called.

<?php
ob_start(); // Start output buffering
header("Location: https://www.example.com");
exit();
ob_end_flush(); // Flush the output buffer
?>