What are common causes of the "headers already sent" error in PHP sessions and how can it be resolved?

The "headers already sent" error in PHP sessions is commonly caused by whitespace or characters being output before session_start() is called. To resolve this issue, make sure that session_start() is the first thing in your PHP code, before any whitespace or HTML output. 

<?php
ob_start();
session_start();

// Rest of your PHP code goes here
?>

Keywords

PHP headers sessions output buffering ob_start

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