Topic on Project:Support desk

I have already defined the following extension in localsettings.php: wfLoadExtension( 'CategoryTree' );

What else do I have to do to display the categories in columns?

see example: http://mathespiele.zum.de/wiki/Kategorie:Einf%C3%BChrung

You're using MediaWiki 1.21, which is unsupported and insecure. Maybe at that time, CategoryTree wasn't being displayed on category pages. This would be a good reason to upgrade your wiki

Thank you very much for your tip. But I use the version 1.32.1 mediawiki.

Thank you. I use the version 1.32.1

Is version 1.32.1 Wiki the one whose example you gave above, or is it a separate Wiki?

There's another wiki. The version is unknown to me. But how can I realize this as shown in the example under version 1.32.1?

The Wiki version can be seen on the Wiki's Spezial:Version page.

Should I then conclude from this that with version 1.32.1 it is no longer possible to realize such a structure as in the example?

To my knowledge, all versions display categories in columns (even here, see example at Category:Extensions used on Wikimedia).

Can you post here an example of how it's displaying on your wiki?

That's what I'd like to do. But my link is recognized as spam while posting.

https://wiki.mittelschule.voehringen.de/index.php?title=Kategorie:Informatik

I'd like a second, third, fourth column.

I think MediaWiki may have an internal limit, if there are few than X pages on that category, it displays them on a single column. This can also be seen here, for example: Category:Extension examples. This doesn't seem to be configurable, though.