Paid Subscription SQL error

[novabandit]

I've just recently implemented paid subscriptions on my forums. Everything seems to be working fine, but each time someone purchased a subscription, I get emailed the following error:

Database error in vBulletin 3.6.4:

Invalid SQL:

SELECT text, languageid, special
FROM phrase AS phrase
LEFT JOIN phrasetype USING (fieldname)
WHERE phrase.fieldname = ''
AND varname = '';

MySQL Error :
Error Number :

Any ideas?

[Steve Machol]

Have you installed any add-ons?

[novabandit]

Quite a few... is this something I should worry about? Or since everything seems to be working, should I just ignore it?

[Steve Machol]

It's possible that error is from an add-on. You can try disabling them for a while to see if the errors stop.