I have recently updated from 1.10.x to 1.12.x

I am also receiving the DB Error #1064 emails.

This is the query listed:
[SELECT COUNT(DISTINCT CASE WHEN THEN A1.ticket_id END) AS q15, COUNT(DISTINCT CASE WHEN A2.state = 'open' THEN A1.ticket_id END) AS q1, COUNT(DISTINCT CASE WHEN A2.state = 'open' AND A2.state = 'open' AND A1.isanswered = '0' THEN A1.ticket_id END) AS q2, COUNT(DISTINCT CASE WHEN (A1.team_id IN (1) OR A1.staff_id IN (3)) AND A2.state = 'open' AND (A1.team_id IN (1) OR A1.staff_id IN (3)) AND A2.state = 'open' AND A1.staff_id IN (3) THEN A1.ticket_id END) AS q6, COUNT(DISTINCT CASE WHEN A2.state = 'closed' AND A2.state = 'closed' AND A1.closed BETWEEN '2019-10-08 00:00:00' AND '2019-10-08 23:59:59' THEN A1.ticket_id END) AS q9, COUNT(DISTINCT CASE WHEN A2.state = 'open' AND A2.state = 'open' AND A1.isanswered = '1' THEN A1.ticket_id END) AS q3, COUNT(DISTINCT CASE WHEN (A1.team_id IN (1) OR A1.staff_id IN (3)) AND A2.state = 'open' AND (A1.team_id IN (1) OR A1.staff_id IN (3)) AND A2.state = 'open' AND NOT A1.staff_id IN (3) THEN A1.ticket_id END) AS q7, COUNT(DISTINCT CASE WHEN A2.state = 'closed' AND A2.state = 'closed' AND A1.closed BETWEEN '2019-10-07 00:00:00' AND '2019-10-07 23:59:59' THEN A1.ticket_id END) AS q10, COUNT(DISTINCT CASE WHEN A2.state = 'open' AND A2.state = 'open' AND A1.isoverdue = '1' THEN A1.ticket_id END) AS q4, COUNT(DISTINCT CASE WHEN (A1.team_id IN (1) OR A1.staff_id IN (3)) AND A2.state = 'open' THEN A1.ticket_id END) AS q5, COUNT(DISTINCT CASE WHEN A2.state = 'closed' AND A2.state = 'closed' AND A1.closed BETWEEN '2019-10-07 00:00:00' AND '2019-10-13 23:59:59' THEN A1.ticket_id END) AS q11, COUNT(DISTINCT CASE WHEN A2.state = 'closed' THEN A1.ticket_id END) AS q8, COUNT(DISTINCT CASE WHEN A2.state = 'closed' AND A2.state = 'closed' AND A1.closed BETWEEN '2019-10-01 00:00:00' AND '2019-10-31 23:59:59' THEN A1.ticket_id END) AS q12, COUNT(DISTINCT CASE WHEN A2.state = 'closed' AND A2.state = 'closed' AND A1.closed BETWEEN '2019-10-01 00:00:00' AND '2019-12-31 23:59:59' THEN A1.ticket_id END) AS q13, COUNT(DISTINCT CASE WHEN A2.state = 'closed' AND A2.state = 'closed' AND A1.closed BETWEEN '2019-01-01 00:00:00' AND '2019-12-31 23:59:59' THEN A1.ticket_id END) AS q14 FROM ost_ticket A1 JOIN ost_ticket_status A2 ON (A1.status_id = A2.id) LEFT JOIN ost_thread A3 ON (A3.object_type = 'T' AND A1.ticket_id = A3.object_id) LEFT JOIN ost_thread_referral A4 ON (A3.id = A4.thread_id) LEFT JOIN ost_staff A5 ON (A4.object_type = 'S' AND A4.object_id = A5.staff_id) LEFT JOIN ost_team A6 ON (A4.object_type = 'E' AND A4.object_id = A6.team_id) LEFT JOIN ost_department A7 ON (A4.object_type = 'D' AND A4.object_id = A7.id) WHERE (A2.state = 'open' AND (A1.staff_id = 3 OR A5.staff_id = 3 OR A1.team_id IN (1) OR A6.team_id IN (1))) OR (A2.state IN ('open', 'closed') AND (A1.dept_id IN (1, 4, 5, 6) OR A7.id IN (1, 4, 5, 6)))]

It seems to be just missing something between the WHEN and the THEN at the start of the query.
So far I can't see anything affected by this reported error though.

Therefor it is not high priority for me but I thought I'd post it anyway.