When filter involves cross references (guess) the SQL query can be very slow and takes down the whole thing (because of the number of parallel queries)
Query that is likely to produce the error:
SELECT id, last_changeset_id FROM (SELECT c.artifact_id AS id, c.id AS last_changeset_id FROM tracker_artifact AS artifact
INNER JOIN tracker_changeset AS c ON (artifact.last_changeset_id = c.id) INNER JOIN cross_references AS A_8859
ON (artifact.id = A_8859.source_id AND A_8859.source_type = 'plugin_tracker_artifact' AND A_8859.target_id = '82975'
OR
artifact.id = A_8859.target_id AND A_8859.target_type = 'plugin_tracker_artifact' AND A_8859.source_id = '82975'
) INNER JOIN (
tracker_changeset_value as CV2
INNER JOIN (
SELECT distinct(field_id) FROM tracker_semantic_status WHERE tracker_id = '402'
) AS SS
ON (CV2.field_id = SS.field_id)
INNER JOIN tracker_changeset_value_list AS CVL
ON (CV2.id = CVL.changeset_value_id)
) ON (CV2.changeset_id = c.id) WHERE (artifact.tracker_id = '402') AND (CVL.bindvalue_id = '15040')) AS R GROUP BY id, last_changeset_id