“Unknown” PHP error - what is that supposed to mea

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.