What are the potential issues when trying to send headers after content has already been output in PHP?

When trying to send headers after content has already been output in PHP, you may encounter the "headers already sent" error. This occurs because headers must be sent before any content is output to the browser. To solve this issue, you can use output buffering to capture the output and prevent it from being sent to the browser until after the headers have been set. 

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

// Output content here

header('Location: https://www.example.com'); // Set header after content

ob_end_flush(); // Flush the output buffer
?>

Keywords

headers_sent ob_start ob_clean output buffering warning: cannot modify header information

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