Cannot Modify Header Information - Working on LocalHost, but not on WebServer?

Question

I'm currently making a Control Panel for my infamous Minecraft Voting System - however am running into a problem. My code works fine on XAMPP - however is not working on my webserver.

I have two pages. One is a login page, and one is an index. The login page simply gets the user info for a SQL database, and checks it, which logs the user in, and redirects using a html meta refresh, as the webserver wasn't allowing PHP headers to be used.

The index page simply says "Welcome $user,". All of this works like a charm on XAMPP, however is not working so great on my webserver. As this error crops up when logging in:

Warning: Cannot modify header information - headers already sent by (output started at /home/linkycra/public_html/MonlotronCP/login.php:3) in /home/linkycra/public_html/MonlotronCP/login.php on line 136

Here is the login.php code - http://puu.sh/1IrEu.png

Here is the index.php code - http://puu.sh/1IrF1.png

Thank you!

possible duplication of http://stackoverflow.com/questions/8028957/headers-already-sent-by-php — sandip, Jan 02 '13 at 13:01

score 1 · Answer 1 · answered Jan 02 '13 at 12:58

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There must some html or white space before your header function please check it.

answered Jan 02 '13 at 12:58

Suresh Kamrushi

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There's no header function. So how can the webserver think there is? – LegacyP7 Jan 02 '13 at 13:08
@sandip, please see my explanation below of why it is happening. Not necessarily use of header() but similar. – kittycat Jan 02 '13 at 13:29

kittycat · Accepted Answer · 2013-01-02T13:28:31.340

You are using setcookie() AFTER you have already sent HTML to the browser. setcookie() will send an HTTP header, but will error since you have already sent HTML before the form. Reason the error only appears when you login as that is when setcookie() is triggered. You can't send a HTTP header once content has already been output to the browser.

The reason it worked on one machine and not the other is one has error_reporting on or set to display, and the other does not, or they are at different error levels. You need to restructure your code where setcookie() is run before you output any content so before <html> and <!DOCTYPE> and any empty spaces.

Thank you very much! Can't believe I forgot to do this :') – LegacyP7 Jan 02 '13 at 20:38 — LegacyP7, Jan 02 '13 at 20:38

score 0 · Answer 3 · answered Jan 02 '13 at 13:10

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check the example on this page: http://php.net/manual/en/function.headers-sent.php

It may help you track down where it's happening

answered Jan 02 '13 at 13:10

Jason

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score 0 · Answer 4 · answered Jan 02 '13 at 13:20

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Could be solved with output buffering, if it's a typo-thing you should solve it instead though.

answered Jan 02 '13 at 13:20

Niclas Larsson

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Cannot Modify Header Information - Working on LocalHost, but not on WebServer?

4 Answers4