Cannot modify header information - headers already sent by (output started at C:\xampp\htdocs\QR_Code Admin\Admin.php:36) in C:\xampp\htdocs\QR_Code Admin\Classes\View.class.php on line 33 code example

Example: Warning: Cannot modify header information - headers already sent by (output started at C:\xampp\htdocs\heermatka\myprofile.php:48) in C:\xampp\htdocs\heermatka\myprofile.php on line 144

ob_start();
Please paste top on the page.