What is causing the "Warning: Cannot modify header information" error in PHP scripts when using Firefox?

The "Warning: Cannot modify header information" error in PHP scripts when using Firefox is typically caused by attempting to modify header information after it has already been sent to the browser. To solve this issue, make sure that no output is sent to the browser before calling functions like header() to modify headers. 

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

// Your PHP code here

ob_end_flush(); // Flush output buffer

Keywords

PHP header information error Firefox browser cache

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