What are some potential causes of the "Cannot send session cookie - headers already sent" error in PHP?

The "Cannot send session cookie - headers already sent" error in PHP occurs when there is output (such as HTML, whitespace, or error messages) sent to the browser before the session_start() function is called. To solve this issue, make sure that session_start() is called at the beginning of the PHP script before any output is sent. 

<?php
// Start the session at the beginning of the script
session_start();

// Rest of the PHP code goes here
?>

Keywords

session cookie headers PHP output buffering ob_start

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