@mlocati the issue is that 0 is passable. `null` wasn't the problem as much as was the change to `> 0`. `$cParentID` is never null. But it is the string '0', which is true when compared like this `'0' != null`. This illustrates the three versions here

http://3v4l.org/BTOVa

`null` never happens. Just that `Page::getCollectionParentIDFromChildID($cID)` returns a string '0' which passed the old `!= null`.

Hope that clears it up,
Mike