How can including a script in PHP lead to header modification errors?

Including a script in PHP can lead to header modification errors if the included script tries to modify headers after they have already been sent to the browser. To solve this issue, ensure that any header modifications are done before any output is sent to the browser, including whitespace or HTML tags. 

<?php
ob_start(); // Start output buffering

// Include script that may modify headers
include 'included_script.php';

ob_end_flush(); // Flush output buffer

Keywords

PHP script inclusion header modification error handling output buffering

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