Taming the Elusive "Headers Already Sent" Error in PHP

This blog targets developers familiar with PHP who encounter the frustrating "Cannot send session cookie" or "Cannot add header information" warnings.

The Culprit:

These warnings indicate your PHP script attempted to send session cookies or headers after some content (like HTML) has already been sent to the browser. Since HTTP headers must come before any content, this creates a conflict.

The Fix:

The solution is simple: make session_start() the very first line of executable code in your script. This ensures headers are sent before any output.

Pro Tip:

For extra security, consider using ob_start() before session_start(). This buffers any accidental output, preventing header conflicts.

Example Code:

<?php
  ob_start();
  session_start();

  // Your script logic here...
?>