Man PHP developers should encounter ”Warning: Cannot modify header information – headers already sent by ….” error before when executing a PHP script.Here are some solutions to this error.1. Blank lineCheck whether there is any blank line after , especially in the files which are used in include() and require(0, some problems are caused by blank lines.2. Add exit() after head()header (“Location: xxx”);exit();3. Use output cache<?php ob_start(); ?>… HTML codes …<?php… PHP codes …header (“Location: ….&rdquo...