警告：session_start（）[function.session-start]：无法发送会话缓存限制器 - 已发送的标头

Question

I've read a lot on other forums, they said that the error was that there was White-space before the session_start but I'm extremely sure there isn't, my file is encoded in UTF8 without BOM so that white-space problem should be fine and it's working perfectly on local (I'm using easyphp). Still, as soon as I put it online, it pops me those problem.anyone can help? They're telling those two lines of error online :

Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent

This is my code:

<?php
session_start();
?>

Answer 1

The warning means that the HTTP headers were already sent and they cannot be modified anymore. You have to make sure you do not send any content before session_start. Put it on top of your very first PHP script, before any echo or HTML and you will be fine.