What is the significance of the warning "Cannot modify header information - headers already sent" in PHP scripts?

The warning "Cannot modify header information - headers already sent" in PHP scripts indicates that some content has already been sent to the browser before attempting to modify header information. To solve this issue, ensure that no content is sent to the browser before calling functions like header() or setcookie(). This can be achieved by moving these functions to the beginning of the script or using output buffering. 

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

// Your PHP code here

ob_end_flush(); // Flush output buffer

Keywords

header PHP warning modify information

Related Questions