How to Fix?Header Already sent.error

How to Fix?Header Already sent.error

Warning: Cannot modify header information - headers already sent by (output started at /home/iesmadeeasy/public_html/config/autoloader.php:59) in /home/iesmadeeasy/public_html/admin/view/layout/offlineStudentZip.php on line 130

No output before sending headers! Functions that send/modify HTTP headers must be invoked before any output is made.

 ob_start(); it will fix error