The extension fails on Mediwiki 1.20.3 with this messager in the apache errorlog: PHP Fatal error: Call to private method LinksUpdate::dumbTableUpdate() from context in /www/docs/wiki/extensions/CategoryIntersection/CategoryIntersection.php on line 86,
Reason: the method LinksUpdate::dumbTableUpdate() (from includes/LinksUpdate.php) is no longer public but private.
There is an additional bug in CategoryIntersection, when a special page is called up.
The Apache log file shows: PHP Fatal error: Cannot override final method SpecialPage::run() in /www/docs/wiki/extensions/CategoryIntersection/CategoryIntersection_body.php on line 154
The problem can be fixed by renaming the internal function from run() to ci_run(), which requires three changes: line 34: $output = $this->ci_run( $lines ); line 52: function ci_run( $lines ) { line 55: $fname = 'CategoryIntersection::ci_run';