After upgrading V1.18.1 when i try to load ticket page from the agent panel. I am getting below PHP_Fatal error:

PHP Fatal error: Uncaught InconsistentModelException: Unable to prepare query: Got error 'repetition-operator operand invalid' from regexp SELECT A1.number AS number, A1.ticket_id AS ticket_id, A1.source AS source, A1.lastupdate AS lastupdate, B2.subject AS cdata__subject, A1.isoverdue AS isoverdue, B3.name AS user__name, B2.priority AS cdata__priority, B4.firstname AS staff__firstname, B4.lastname AS staff__lastname, B5.name AS team__name, A1.team_id AS team_id, A2.id AS status__id, A1.created AS created, A1.isoverdue = '1' AS b/UbbBm, B2.priority REGEXP '\"?(?<![0-9])4(\"|,|$)' AS wD6Rq8G, A1.isanswered = '0' AS 2GkBZxz, (SELECT COUNT(R0.id) AS count FROM ost_thread Q7 JOIN ost_ticket Q8 ON (Q7.object_type = 'T' AND Q7.object_id = Q8.ticket_id) LEFT JOIN ost_thread_entry R0 ON (Q7.id = R0.thread_id) WHERE Q8.ticket_id = A1.ticket_id AND NOT R0.flags & 4 != 0) AS _thread_count, (SELECT COUNT(R1.id) AS count FROM ost_thread Q7 JOIN ost_ticket Q8 ON (Q7.object_type = 'T' AND Q7.object_id = Q8.ticket_id) LEFT JOIN ost_thread_entry R0 ON (Q7.id = R0.thread_id) LEFT JOIN ost_attachment R1 ON (R1.type = 'H' AND R0.id = R1.object_id) WHERE Q8.ticket_id = A1.ticket_id AND R1.inline = 0) AS _att_count, B6.expire > NOW() AND NOT B6.staff_id = 486 AS _locked, (SELECT COUNT(R0.id) AS count FROM ost_thread Q7 JOIN ost_ticket Q8 ON (Q7.object_type = 'T' AND Q7.object_id = Q8.ticket_id) LEFT JOIN ost_thread_collaborator R0 ON (Q7.id = R0.thread_id) WHERE Q8.ticket_id = A1.ticket_id) AS _collabs, COALESCE(B4.firstname, B4.lastname, B5.name, 'zzz') AS assignee 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_thread A6 ON (A1.ticket_id = A6.object_id AND A6.object_type = 'C') LEFT JOIN ost_thread_referral A7 ON (A6.id = A7.thread_id) LEFT JOIN ost_staff A8 ON (A7.object_type = 'S' AND A7.object_id = A8.staff_id) LEFT JOIN ost_department B0 ON (A4.object_type = 'D' AND A4.object_id = B0.id) LEFT JOIN ost_department B1 ON (A7.object_type = 'D' AND A7.object_id = B1.id) LEFT JOIN ost_ticket__cdata B2 ON (A1.ticket_id = B2.ticket_id) LEFT JOIN ost_user B3 ON (A1.user_id = B3.id) LEFT JOIN ost_staff B4 ON (A1.staff_id = B4.staff_id) LEFT JOIN ost_team B5 ON (A1.team_id = B5.team_id) LEFT JOIN ost_lock B6 ON (A1.lock_id = B6.lock_id) WHERE A1.isanswered = '1' AND NOT (A1.team_id = 0 AND A1.staff_id = 0) AND A1.isoverdue = '1' AND A2.state = 'open' AND ((A2.state = 'open' AND (A1.staff_id = 486 OR A5.staff_id = 486 OR A6.object_type = 'C' AND A8.staff_id = 486)) OR A1.dept_id IN (37, 93) OR B0.id IN (37, 93) OR A6.object_type = 'C' AND B1.id IN (37, 93)) AND (A1.ticket_pid IS NULL OR A1.flags & 8 != 0) GROUP BY A1.ticket_id ORDER BY A1.created DESC LIMIT 50 in C:\wamp64\www\ost\include\class.orm.php:3483
Stack trace:
#0 C:\wamp64\www\ost\include\class.orm.php(3529): MySqlExecutor->execute()
#1 C:\wamp64\www\ost\include\class.orm.php(2104): MySqlExecutor->getArray()
#2 C:\wamp64\www\ost\include\class.orm.php(2054): HashArrayIterator->{closure}()
#3 C:\wamp64\www\ost\include\class.orm.php(2033): CallbackSimpleIterator->next()
#4 C:\wamp64\www\ost\include\class.orm.php(2042): CallbackSimpleIterator->rewind()
#5 C:\wamp64\www\ost\include\class.orm.php(1713): CallbackSimpleIterator->valid()
#6 C:\wamp64\www\ost\include\class.orm.php(1723): CachedResultSet->fillTo(9223372036854775807)
#7 C:\wamp64\www\ost\include\class.orm.php(1739): CachedResultSet->asArray()
#8 C:\wamp64\www\ost\include\staff\templates\queue-tickets.tmpl.php(264): CachedResultSet->getIterator()
#9 C:\wamp64\www\ost\scp\tickets.php(569): require_once('C:\wamp64\www\o...')
#10 {main}
thrown in C:\wamp64\www\ost\include\class.orm.php on line 3483

Can you please help me on that? becuase of above error some of my agents are get broken html on ticket list