Forum Error 1064 when updating to 4.2.0
 

I tried to update mine forum from 4.0.8 to 4.2.0 but it failed. Plugins are disabled when running the update.

An error has occurred with your database. Please contact vBulletin Support for assistance.
Module: postrelease, Step 1 Database Error:1064
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 'WHERE NOT EXISTS ( SELECT secretkey FROM postrelease LIMIT 1 )' at line 6
Query:
INSERT INTO postrelease
(secretkey)
(SELECT '0XRCmPtgWE'
FROM DUAL
WHERE NOT EXISTS
(
SELECT secretkey
FROM postrelease
LIMIT 1
)):

Any ideas?