Thread:Project:Support desk/Category not displaying in v1.19.2/reply (3)

According to the talk in Extension:CategoryTree, it seems to be incompatible or have bugs with recent installations. Maybe the version you downloaded isn't compatible with the mediawiki version you're running.

If you're using version 1.20, try downloading the snapshot (link in the extension page).

Alternatively, you can disable this extension deleting the require_once( "$IP/extensions/CategoryTree/CategoryTree.php" ); in LocalSettings.php