PHP Warning trying to access array offset on value of type null

[itangir]

I'd say 95% of my wiki's error log (Apache) is this:

PHP Warning:  Undefined array key 0 in C:\\UniServer\\www\\dokuwiki\\lib\\plugins\\include\\action.php on line 285
PHP Warning:  Trying to access array offset on value of type null in C:\\UniServer\\www\\dokuwiki\\lib\\plugins\\include\\action.php on line 285

Not sure if that just means an array needs to be checked before being accessed?

It's not actually affecting anything, as far as I know. Other than cluttering up the log. I just noticed it when trying to track down some other issue and thought I'd mention it.

[fiwswe]

It generally helps to provide at least the following information for any issues reported here:

• DokuWiki version
• Include plugin version
• PHP version and method of invocation (mod_php or php-fpm)
• Server operating system and version
• If possible the page source for a page that generates one of these warnings (preferably reduced to the minimum amount of source that causes the warning)
• Anything else that might be relevant such as the template used or other active plugins

FWIW: I do not see these warnings on:
Release 2025-05-14b "Librarian"
PHP 8.3.26
OpenBSD 7.7
fpm-fcgi
Include plugin 2025-07-22

[itangir]

Thanks for the guidance. Here's some info:

• Release 2025-05-14b "Librarian"
• PHP 8.1.11
• Windows NT 10.0 [Windows Server 2019 10.0.17763.7919]
• apache2handler [mod_php]
• Include plugin 2025-07-22 [Recently updated, although did not resolve warnings]

I just tried creating a bare bones page with this as the only data:

{{section>tech:servery:management:drac#ssd&noheader}}

Upon load, that gave me a few of these:

[Thu Oct 30 09:00:58.198402 2025] [php:warn] [pid 6012:tid 2044] [client 10.10.39.26:59564] PHP Warning:  Undefined array key 0 in C:\\UniServer\\www\\dokuwiki\\lib\\plugins\\include\\action.php on line 285, referer: https://wiki.contoso.org/doku.php?id=tech:sites:contoso:contoso_app
[Thu Oct 30 09:00:58.214611 2025] [php:warn] [pid 6012:tid 2044] [client 10.10.39.26:59564] PHP Warning:  Trying to access array offset on value of type null in C:\\UniServer\\www\\dokuwiki\\lib\\plugins\\include\\action.php on line 285, referer: https://wiki.contoso.org/doku.php?id=tech:sites:contoso:contoso_app

Other plugins enabled on this system:

acl
authad
authorstats
authplain
cellbg
changes
config
copy2clipboard
csv
datatables
dw2pdf
edittable
extension
fastwiki
gallery
include
info
logviewer
mermaid
move
note
pagelist
popularity
revert
safefnrecode
smtp
sortablejs
styling
typography
upgrade
usermanager
vshare
wrap

I might be able to try temporarily disabling most of them after hours to see if it still happens.

Other context: I don't deal with web administration much at all in my position. It's kind of an "as-needed" hat that I wear. And that probably translates to less than a couple times a year. If there's anything else I can do to give better info, let me know and I'll get to it as I'm able to.

[fiwswe]

That is much better information.

Your version of PHP is rather old and no longer supported. But that is probably not the cause of the issue. Still, if you can, bring the version up to at least PHP 8.3.27, though PHP 8.4.14 would be even better.

My systems no longer have packages for PHP 8.1 so I can't test whether the version makes any difference.

Does the referenced page tech:servery:management:drac exist and does it contain a heading ssd?

I did a some similar tests in one of my wikis (see above for the versions) and did not get any warnings.
{{section>test:ns2:ns3:some_existing_name#some_existing_heading&noheader}}
{{section>test:ns2:ns3:some_existing_name#some_nonexisting_heading&noheader}}
{{section>test:ns2:ns3:some_nonexisting_name#some_heading&noheader}}

I'm not sure any other plugin could cause these warnings. You could test by temporarily disabling any non-standard plugins.

[itangir]

Maybe just something wrong with my particular configuration then. Thanks for checking.

I should point out that everything is working fine... All the pages that use include work and load just fine; I just get those warnings in the log for some reason. That page and header that I use in my example do exist and work and display with no issue in the browser.

I will try and get the server and PHP updated in the next week or so, hopefully that will also fix whatever is going on. If not, I'll try disabling plugins temporarily. If I find anything concrete or useful, I'll let you know.

[fiwswe]

Ok.

Maybe just something wrong with my particular configuration then.

My only non-default setting for the Include plugin in conf/local.php is:
$conf['plugin']['include']['showmdate'] = 1;

Not sure if that just means an array needs to be checked before being accessed?

Maybe. The problem is that avoiding the warning may just hide an issue that has its root cause somewhere else. But I don't pretend to understand the inner workings of the Include plugin. Someone with more knowledge would need to make that decision.

[itangir]

Was able to update to PHP 8.3.0. Still get the warnings but I did find something new out.

Apparently the code I had in my test page was fine, it was when I went back and forth between my start page and test page that the error occurred and the actual warning was being caused by the start page. I alternated loading between a different page and my test page and couldn't reproduce the issue.

I then modified my test page to be the same as the start page and kept whittling away at the code until I could reproduce the issue with just one line:

{{page>tech:bottom&noindent}}

Changing the path to a different page (e.g. tech:misc) doesn't seem to matter so I don't think it's an issue with the page it is referencing.

My log seems to have an additional line when I was testing although the time difference might suggest it's not related to this specific issue. But here's the logging anyway:

[Sat Nov 01 11:56:04.238960 2025] [php:warn] [pid 11328:tid 1912] [client 10.10.39.26:51489] PHP Warning:  Undefined array key "title" in C:\\UniServer\\www\\dokuwiki\\lib\\plugins\\include\\action.php on line 101, referer: https://wiki.contoso.org/doku.php?id=tech:sites:monstro:monstro_app
[Sat Nov 01 11:56:22.634147 2025] [php:warn] [pid 11328:tid 1912] [client 10.10.39.26:51499] PHP Warning:  Undefined array key 0 in C:\\UniServer\\www\\dokuwiki\\lib\\plugins\\include\\action.php on line 285, referer: https://wiki.contoso.org/doku.php?id=tech:sites:contoso:vendors
[Sat Nov 01 11:56:22.649773 2025] [php:warn] [pid 11328:tid 1912] [client 10.10.39.26:51499] PHP Warning:  Trying to access array offset on null in C:\\UniServer\\www\\dokuwiki\\lib\\plugins\\include\\action.php on line 285, referer: https://wiki.contoso.org/doku.php?id=tech:sites:contoso:vendors

[fiwswe]

Was able to update to PHP 8.3.0.

Better, but why didn't you upgrade to the latest version of PHP 8.3, i.e. PHP 8.3.27, while you were at it? You are missing out on a lot of fixes, some even relevant for security.

Still, this is probably not related to your issue.

Changing the path to a different page (e.g. tech:misc) doesn't seem to matter so I don't think it's an issue with the page it is referencing.

To verify this. maybe a more controlled environment would help? Create 2 pages test:test_include and test:included_content and then start out with very simple content such as:

====== Test Include ======

{{page>test:included_content&noindent}}

====== Included Content ======

Blah.

I did exactly that in my test wiki and saw no warnings.

Note that, in case that makes any difference, my configuration was updated to:
PHP 8.4.14
OpenBSD 7.8

My log seems to have an additional line when I was testing although the time difference might suggest it's not related to this specific issue.

plugin-include/action.php

Line 101 in af0799c

$event->data['metadata'] = array('title' => $meta['title']);

Seems unsafe, as it assumes that $meta['title'] exists. I could not find any previous check that this assumption is correct (and there are apparently situations where it isn't). This would probably be better, though I'm not sure whether null or '' would be the better default replacement:

$event->data['metadata'] = array('title' => $meta['title'] ?? null);

Or maybe even skip saving like this:

if (array_key_exists('title', $meta))
    $event->data['metadata'] = array('title' => $meta['title']);

or

if (array_key_exists('title', $meta))
    $event->data['metadata'] = array('title' => $meta['title']);
else
    $event->data['metadata'] = [];

However this warning does seem unrelated to the warnings in line 285.

---

It does seem to me that the code of the Include plugin makes very little effort to check that array keys exist before using them. In other words, it makes a lot of assumptions — something that should be avoided in robust code. With PHP getting more strict as it evolves, maybe a general code review would be in order?

[itangir]

Better, but why didn't you upgrade to the latest version of PHP 8.3, i.e. PHP 8.3.27, while you were at it? You are missing out on a lot of [fixes](https://www.php.net/ChangeLog-8.php#8.3.27), some even relevant for security.

This wiki is hosted using Uniform Server, and their latest offering (15.0.2) only includes PHP 8.3.0. Although they seemed to not have dropped any new releases since late 2023 so perhaps it is abandoned and we'll need to migrate sooner than later. I'd probably prefer to just migrate it to debian at this point, but those are bigger waves than I have time to make right now. For an intranet wiki that cannot be accessed externally, (non-documentation) work on it tends to get relegated to low priority.

Ok, I was able to confirm I do not get the warnings when using your test pages. So I started breaking down the content of my problematic included pages and I think I've got it simplified down to:

<WRAP box>
===== Test =====
</WRAP>

My server seems to reproduce the warning whenever the included content contains a headline level of 4 (or higher) inside a WRAP box. Possibly in other WRAP elements as well; I did not test.

Not sure if that's too specific an issue to develop a fix for or not, but hopefully it's reproducible for others as well.

[fiwswe]

Hmm, no warnings here with this included page:

====== Included Content ======

<WRAP box>
===== Test =====
</WRAP>

I also tested this with no issues:

====== Included Content ======

<WRAP box>
===== Test =====
</WRAP>

<WRAP box>
==== Test ====
</WRAP>

<WRAP box>
=== Test ===
</WRAP>

<WRAP box>
== Test ==
</WRAP>

[fiwswe]

Ah got it now! This does trigger the warning:

<WRAP box>
===== Test =====
</WRAP>

Same as:

<WRAP>
===== Test =====
</WRAP>

and

<WRAP>
==== Test ====
</WRAP>

So the missing page title is the problem it seems. But a simple page like this does not trigger the warning:

Test

It's good to have a reproducible and simple example. Maybe now someone can figure out what the problem is in the Include plugin source.