Derek wrote:

The following statement causes an error to be written to the sql error log.
This has been noticed when cron is running (although not for every cron run)

SELECT * FROM mdl_mod/oublog WHERE id = '14892' LIMIT 1

This has been identified due to an incorrect setting for the tag instance type
(mod/oublog) when an oublog tag is set (The tag instance type should be just
'oublog')