I am creating a site using the registration system in chapter 18, and I am using the output buffer on every page, the ob_start() is included in every page via the header.html file.
In the book it says that if we use the output buffer we won't get headers already sent error messages. But I just tested it and put a space before the starting <?php tag.
And I got the following error.
Warning: session_start() [function.session-start]: Cannot send session cookie - headers already sent by (output started at /home/
why does it give an error message.