Programming Forums > Web Development and Design > PHP

stu7398 · Jan 12th, 2008, 8:06 AM

I am looking for my contact form when submitting, to redirect to a 'thank you' page, however I receive the following error.
Warning: Cannot modify header information - headers already sent by (output started at

I am new to php programming; clear instructions or language is appreciated.

Thanks.

Sane · Jan 12th, 2008, 8:37 AM

The function, "header", can not be called if you've already made the script output text to the client.

For example:

 PHP Syntax (Toggle Plain Text) 
<?php
 
echo 'Hello World!'
header('Content-type: text/plain');
 
?>
<?php

echo 'Hello World!'
header('Content-type: text/plain');

?>

Will throw an error, because it tried to modify the header after all of the headers were sent to the client.

 PHP Syntax (Toggle Plain Text) 
<?php
 
header('Content-type: text/plain');
echo 'Hello World!'
 
?>
<?php

header('Content-type: text/plain');
echo 'Hello World!'

?>

This will work. Because the header is modified, and then output is sent.

Jimbo · Jan 12th, 2008, 11:30 AM

Also of note, the PHP code must be the first thing in the file. The following will not work:

(Toggle Plain Text)

<!DOCTYPE blah blah blah>
<?php
    header('foo');
?>

Ooble · Jan 14th, 2008, 12:14 AM

If you still want to supress the error, you can do so by calling the error_reporting function. Or, if you want to do it for all files, edit the php.ini file - check the line beginning with "error_reporting = ".

If this is your production server, turning display_errors off and log_errors on in your php.ini file is recommended, so if there are any errors, your users don't see them but you do. If it's your development server, I'd recommend the opposite - set error_reporting to E_ALL, display_errors to On and log_errors to Off.

FERDIKUCUK · Feb 18th, 2008, 8:06 AM

(Toggle Plain Text)

<?php 
ob_start();session_start();
echo "ferdi kucuk";
header("location : url");
?>

ob_start();

Jan 12th, 2008, 8:06 AM	#1
stu7398 Newbie Join Date: Jan 2008 Posts: 3 Rep Power: 0	Warning: Cannot modify header information - headers already sent by (output started at I am looking for my contact form when submitting, to redirect to a 'thank you' page, however I receive the following error. Warning: Cannot modify header information - headers already sent by (output started at I am new to php programming; clear instructions or language is appreciated. Thanks.

Jan 12th, 2008, 8:37 AM	#2
Sane Programming Guru Join Date: Apr 2005 Posts: 1,799 Rep Power: 5	Re: Warning: Cannot modify header information - headers already sent by (output started at The function, "header", can not be called if you've already made the script output text to the client. For example: PHP Syntax (Toggle Plain Text) <?php echo 'Hello World!' header('Content-type: text/plain'); ?> <?php echo 'Hello World!' header('Content-type: text/plain'); ?> Will throw an error, because it tried to modify the header after all of the headers were sent to the client. PHP Syntax (Toggle Plain Text) <?php header('Content-type: text/plain'); echo 'Hello World!' ?> <?php header('Content-type: text/plain'); echo 'Hello World!' ?> This will work. Because the header is modified, and then output is sent.

Jan 12th, 2008, 11:30 AM	#3
Jimbo Battle Programmer Join Date: Feb 2006 Location: Bellevue, WA, USA Posts: 747 Rep Power: 3	Re: Warning: Cannot modify header information - headers already sent by (output started at Also of note, the PHP code must be the first thing in the file. The following will not work: (Toggle Plain Text) <!DOCTYPE blah blah blah> <?php header('foo'); ?> <!DOCTYPE blah blah blah> <?php header('foo'); ?> __________________ <insert disclaimer here> <insert shameless plug for Visual Studio here>

Jan 14th, 2008, 12:14 AM	#4
Ooble I eat cake for breakfast. Join Date: Jul 2004 Location: In my box. Posts: 4,434 Rep Power: 9	Re: Warning: Cannot modify header information - headers already sent by (output started at If you still want to supress the error, you can do so by calling the error_reporting function. Or, if you want to do it for all files, edit the php.ini file - check the line beginning with "error_reporting = ". If this is your production server, turning display_errors off and log_errors on in your php.ini file is recommended, so if there are any errors, your users don't see them but you do. If it's your development server, I'd recommend the opposite - set error_reporting to E_ALL, display_errors to On and log_errors to Off. __________________ Me :: You :: Them

Feb 18th, 2008, 8:06 AM	#5
FERDIKUCUK Php Coder Join Date: Feb 2008 Posts: 5 Rep Power: 0	Re: Warning: Cannot modify header information - headers already sent by (output started at (Toggle Plain Text) <?php ob_start();session_start(); echo "ferdi kucuk"; header("location : url"); ?> <?php ob_start();session_start(); echo "ferdi kucuk"; header("location : url"); ?> ob_start(); __________________ All in one programming Articles Site

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