Codeigniter: Message: Cannot modify header information - headers already sent by (output started at [duplicate]

Question

I have created a dynamic menu CMS website. I developed in a Windows system. When i run my project in windows operating system, My project runs without any error. But now uploaded it into Linux Operating system server i am getting warning & error like:

    A PHP Error was encountered

    Severity: Warning

    Message: Cannot modify header information - headers already sent by (output started at /home/ansofcm8/public_html/apps/resources/math/application/core/MY_Controller.php:1)

    Filename: libraries/Session.php

    Line Number: 675

What could be the reason. Please help me.

Answer 1

There seems to be whitespace before the php open tag <?php in MY_Controller.php.

Check all PHP files and remove the whitespace before the <?php tag. If there is a space or new line, the body of the http request is started, and you can't add new headers to the http request.