Issue: MySQL Error with Convert Legacy Code to BB-Code

Database error in vBulletin 3.7.6:

Invalid SQL:

		SELECT post.postid, post.pagetext, thread.forumid, thread.title,
			thread.firstpostid, thread.threadid,
			post.userid, user.usergroupid, user.membergroupids
		FROM vb3_thread AS thread
		LEFT JOIN vb3_post AS post ON (post.postid = thread.firstpostid)
		LEFT JOIN vb3_user AS user ON (post.userid = user.userid)
		WHERE thread.threadid IN ()
		GROUP BY thread.threadid
		ORDER BY post.postid DESC
		LIMIT 50,50;

MySQL Error   : You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ')
		GROUP BY thread.threadid
		ORDER BY post.postid DESC
		LIMIT 50,50' at line 7
Error Number  : 1064
Request Date  : Thursday, April 9th 2009 @ 11:18:28 AM
Error Date    : Thursday, April 9th 2009 @ 11:18:29 AM
Script        : hxxp://www.mysite.com/forum/admincp/vaultwiki.php?do=convert&startat=50&pp=50
Referrer      : hxxp://www.mysite.com/forum/admincp/vaultwiki.php?do=convert
IP Address    : ????????
Username      : ???????
Classname     : vB_Database
MySQL Version : 5.0.67-community