How can one prevent the error message related to session_start() when headers have already been sent?

When headers have already been sent, calling session_start() will result in an error message. To prevent this, ensure that session_start() is called before any output is sent to the browser, including whitespace. One common solution is to move the session_start() function to the very beginning of your PHP script, before any HTML or whitespace. 

<?php
// Start the session before any output is sent
session_start();

// Rest of your PHP code goes here
?>

Keywords

session_start headers output buffering ob_start ob_end_flush

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