session_start() throwing error

Question

I am currently getting the following error using php:

Warning: session_start() [function.session-start]: 
Cannot send session cache limiter - headers already sent 
(output started at /home/paramireze/madisonh3.com/calendar.php:1)
in /home/paramireze/madisonh3.com/includes/common.php on line 5

The first line of every file is include common.php, and the first line of code in common.php is 'if(!isset($_SESSION)) {session_start();}`.

This error only occurs on calendar.php and news.php (you can see the error if you visit http://www.madisonh3.com/calendar.php). All my files are the same, which includes a common.php. After that, I will write the html tag and include the header from there.

I've read other discussions regarding session_start and all say to make sure you do not output any html before session_start. Also, if I am doing something wrong, why is it only happening to two out of my 10 files?

possible duplicate of [session\_start() error](http://stackoverflow.com/questions/5205666/session-start-error) — mario, Mar 07 '13 at 20:09
possible duplicate of [Headers already sent by PHP](http://stackoverflow.com/questions/8028957/headers-already-sent-by-php) — mario, Mar 07 '13 at 20:10

score 2 · Accepted Answer · answered Mar 07 '13 at 19:58

2

There is something outputting data BEFORE your session_start() command. As the session cookie is set to the HTTP header it must precede any HTML output.

The error Cannot send session cookie - headers already sent by (output started at /home/paramireze/madisonh3.com/calendar.php:1) in /home/paramireze/madisonh3.com/includes/common.php on line 5 indicates something is outputted before.

So look into your code and find what could be echoing data before your session_start().

answered Mar 07 '13 at 19:58

jtheman

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session_start is the first line of every file using an include – paul Mar 07 '13 at 20:00
No when I view your source I find `
`before the error message... – jtheman Mar 07 '13 at 20:01
I don't, which sucks I get the following – paul Mar 07 '13 at 20:07
Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /home/paramireze/madisonh3.com/calendar.php:1) in /home/paramireze/madisonh3.com/includes/common.php on line 5
– paul Mar 07 '13 at 20:07
There's no magic here. Even a whitespace or a newline before your include might cause this to happen. There IS an output made from your script(s) before the session_start() and as other script including the same file seem to work you should look into the calendar.php file. – jtheman Mar 07 '13 at 20:09

martinstoeckli · Answer 2 · 2013-03-07T20:18:59.120

You should care that your editor does not store the utf-8 BOM header, this header is sometimes stored at the begin of the file with 3 bytes ï»¿.

The editor will hide them, so if you are not sure if your file contains these characters, you can either use a non interpreting editor (hex editor), or this wonderful online W3C checker. The BOM header is treated as output by PHP, and this can cause nasty Cannot modify header information - headers already sent errors.

Checking your URL shows, that there is indeed such a BOM header. Have a look at the settings of your editor (IDE).

session_start() throwing error

2 Answers2