Cannot modify header information - headers already sent
 

Warning: Cannot modify header information - headers already sent

Warning: Cannot modify header information - headers already sent by (output started at C:\webserver\Apache2\htdocs\register.php:1) in C:\webserver\Apache2\htdocs\register.php on line 68

Re: Cannot modify header information - headers already sent
 

You have some output like echo / print before the final output you are doing again which means you are sending the headers couple of times

Re: Cannot modify header information - headers already sent
 

use output buffering, call the function ob_start and the beginning of your script.