session_start() error since today

Since today in all my apps this error started to show:

Warning: session_start() [function.session-start]: Cannot send session cache lim开发者_运维技巧iter - headers already sent (output started at /home/fb/index.php:5) in /home/fb/facebook.php on line 37

What changes ware made by Facebook today and how can I fix this?

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You should remove any code above session_start(). Generaly this function sould be executed before any output. (For example HTML code)

Another posibility it that the file encoding is not correct. Check for spaces and etc. before session_start().

// whitespace, any mark up or include that displays something <HERE>
// it will give you that error
<?php
session_start();