Warning: Cannot modify header information - headers already sent by (output started at D:\xampp\htdocs\admin\header.php:1) in D:\xampp\htdocs\admin\companies.php on line 31 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.