PHP seems to execute script twice

Question

My web server is acting wierd. It seems like it executes scripts (PHP) twice before sending then to apache.

I've run this file:

<?php
echo '<pre>';
session_start();
$_SESSION['index']++;
echo '<br>';
print_r($_SESSION);
?>

And I know that ++ will give a notice at first, but it's just to investigate if it runs twice. Anyway, the printed session shows that the index-index increases by two each time you load the page.

The webserver is apache2, php5 installed on a debian unit.

Anyone has any ideas?

What happens if you hit it with something else, such as `wget`? — Dark Falcon, Feb 19 '13 at 20:43
Do you have any apache rewrite, and 404? Check your requests to server. — , Feb 19 '13 at 20:44
Is that all you are running or is it included in something else. — jeroen, Feb 19 '13 at 20:44
did you tried on a command line ? (you will need php5-cli installed first) — Abu Romaïssae, Feb 19 '13 at 20:47
things to check on twice behaviour: http://stackoverflow.com/questions/5948063/rewriterule-causes-page-to-reload-twice/5948301#5948301, this is why testing it with wget or the way you run your script is important — regilero, Feb 19 '13 at 20:49
That is all that I am running. Navigating to server/index.php, and index.php has only the content i showed — jorel, Feb 19 '13 at 20:51
@regilero Chrome request area did just catch the index.php-request. No other. — jorel, Feb 19 '13 at 20:54
@jorel: so you have your answer. id does not come from server. chances are that the favicon request or any other hidden browser request listed in the check list is hurting you. — regilero, Feb 19 '13 at 21:02
I tried using fwrite instead of session now. Got 3 appended lines each load.... :) — jorel, Feb 19 '13 at 21:40

score 6 · Accepted Answer · answered Feb 19 '13 at 20:44

6

echo '<pre>'; //Headers and cookies already sent.
session_start(); //Cannot set cookie anymore, system tries again, I guess

Start session first, then output anything. Try placing session_start(); on top

answered Feb 19 '13 at 20:44

sybear

7,837
1
22
38

Do all your scripts get executed twice? Or just this? – sybear Feb 19 '13 at 20:52
Well, first I tried with some other code, then saw that it behaived wierd, so I created this script to test things. – jorel Feb 19 '13 at 20:53
Did you try some really simple code without headers and `session_start()` ? – sybear Feb 19 '13 at 20:54
Well, how do I test it runs twice then? – jorel Feb 19 '13 at 20:55

I had the issue and the culprit was

 right after mysql query run making the script containing the query running twice. I deleted all  and print_r() from the script until it reaches  and it stopped executing twice. I could do this or use ob_start(). Thank you!

– Daniel Jan 29 '22 at 17:19

score 3 · Answer 2 · answered Dec 04 '16 at 00:06

3

Oke folks, found a completely insane solution to this problem. Just posting for future reference. I recently installed a HTML validator in Chrome (an extension). This seems to be the culprit. After everything has loaded, the validator seems to be re-requesting the page so it is executed twice. Nice plugin. Not! Took me about half a day to figure this out.

answered Dec 04 '16 at 00:06

Pianoman

327
2
10

This solution saved me tons of hours, +1, thank you! – Tomer Gal Nov 29 '19 at 11:39

score 2 · Answer 3 · answered Jul 11 '13 at 07:53

I can't thank the poster of this question enough. His session test made me realize that I had the same problem of a php script running several times.

In my script I had two PDO functions seperated from each other by an if-else-construct. One was a simple select, and one a simple insert function. But everytime I ran the script, both pdo commands got executed. PDO ended up writing rows in my table which had the entry 'public'.

So what happened? My page got send multiple times because of ELEMENTS IN THE HTML CODE THAT COULD NOT BE FOUND. In my case that was a css file which was named incorrectly. When I solved that (after 4 hours of looking at code) the problem disappeared. Also broken images for example trigger the same event.

Had the same problem.... Google Chrome showed 404's on css-files. Solved those but still script gets executed twice. — Pianoman, Dec 03 '16 at 23:31

score 0 · Answer 4 · answered Jun 29 '16 at 04:17

I am seeing the same behaviour... a $_POST would be present the first time the page ran, then wouldn't the second time... scoured the code to find why the page might be posting back to itself again. No avail.

After seeing user1601869's answer above, I started checking. I had some links to stylesheets I hadn't written yet, so put skeletons of those in.

It turns out that for me, the culprit was:

<link rel="shortcut icon" href="">

This was just a placeholder for an icon that was causing my page to break. I suggest that if you have the same problem, look for links in the <HEAD></HEAD> that are broken!

PHP seems to execute script twice

4 Answers4

Linked