If you search for part of the error message like maybe "vBForum_Item_SocialGroupDiscussion", you'll find a lot of threads mentioning it. You can edit the two files mentioned in the error message and make the lines look like what it shows in the error message (I think you just have to add the = '' after $required_query), or you can suppress all displayed messages by adding
PHP Code:
define('DISPLAY_DS_ERRORS', false);
to your config.php. Or you can upgrade to 4.2.3, which would probably be the best idea (but it does need at least php 5.4).