How can the error message "Cannot modify header information - headers already sent" be resolved in PHP?

The error message "Cannot modify header information - headers already sent" occurs when there is output (such as whitespace) before PHP attempts to send headers. To resolve this issue, ensure that there is no output (including whitespace) before calling functions like header() or setcookie(). One common solution is to move all header-related functions to the top of the PHP file before any HTML or other output. 

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

// Your PHP code here

ob_end_flush(); // Flush the output buffer

Keywords

output buffering ob_start ob_end_flush header whitespace

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