Undefined index - what does it mean?


Well-known member
Hey there,

i've updated my site from 1.1.3 to 1.2 and now i've encountered a couple of errors in a custom addon someone made for me.

The main errors are like "Undefined index: XenForo_NewsFeedHandler_DiscussionMessage_ProfilePost". What does it mean? Is it possible to just define an index?

I'm not an expert in development but i have some basic skills, so i know what i'm doing. :)

Thanks for your help


Chris D

XenForo developer
Staff member
You can have an array of data, e.g.

$array = array(
     'someKey1' => 'someValue1',
     'someKey2' => 'someValue2'
someKey1 and someKey2 are indexes of that array.

To better instruct how to fix, we'd probably need to see the full error message (including the line numbers and stack trace) and know what the add-on is supposed to do.

The index it is reporting is a bit confusing because that's a class name, but perhaps the code contains an array of class names for some purpose...

Yeah getting a better idea of what the code is doing is needed.