问题
Possible Duplicate:
How to fix “Headers already sent” error in PHP
[Mon Jan 10 21:01:26 2011] [error] [client xx.xx.xxx.xx] PHP Warning: Cannot modify header information - headers already sent in Unknown on line 0, referer: www.example.com/some.php
Why PHP is not able to locate where the headers were sent from?
回答1:
See if you have a space after <?. The header function is quite sensitive and doesnt work if anything is outputted before hand.
来源：https://stackoverflow.com/questions/4651548/unknown-php-error-what-is-that-supposed-to-mean