bad query: 
                WITH visitor AS (
            INSERT INTO website_visitor (
                partner_id, access_token, last_connection_datetime, visit_count, lang_id,
                website_id, timezone, write_uid, create_uid, write_date, create_date, country_id)
            VALUES (
                8, 8, now() at time zone 'UTC', 1, 1,
                1, 'Australia/Sydney', 7, 7,
                now() at time zone 'UTC', now() at time zone 'UTC', (
                    SELECT id FROM res_country WHERE code = NULL
                )
            )
            ON CONFLICT (access_token)
            DO UPDATE SET
                last_connection_datetime=excluded.last_connection_datetime,
                visit_count = CASE WHEN website_visitor.last_connection_datetime < NOW() AT TIME ZONE 'UTC' - INTERVAL '8 hours'
                                    THEN website_visitor.visit_count + 1
                                    ELSE website_visitor.visit_count
                                END
            RETURNING id, CASE WHEN create_date = now() at time zone 'UTC' THEN 'inserted' ELSE 'updated' END AS upsert
        , 'https://156611-17-0-all.runbot10.willdooit.net/shop/furn-6666-acoustic-bloc-screens-23' AS url, NULL AS page_id
                ), track AS (
                    INSERT INTO website_track (visitor_id, url, page_id, visit_datetime)
                    SELECT id, url, page_id::integer, now() at time zone 'UTC' FROM visitor
                )
                SELECT id, upsert from visitor;
ERROR: could not serialize access due to concurrent update

bad query: 
                WITH visitor AS (
            INSERT INTO website_visitor (
                partner_id, access_token, last_connection_datetime, visit_count, lang_id,
                website_id, timezone, write_uid, create_uid, write_date, create_date, country_id)
            VALUES (
                8, 8, now() at time zone 'UTC', 1, 1,
                1, 'Australia/Sydney', 7, 7,
                now() at time zone 'UTC', now() at time zone 'UTC', (
                    SELECT id FROM res_country WHERE code = NULL
                )
            )
            ON CONFLICT (access_token)
            DO UPDATE SET
                last_connection_datetime=excluded.last_connection_datetime,
                visit_count = CASE WHEN website_visitor.last_connection_datetime < NOW() AT TIME ZONE 'UTC' - INTERVAL '8 hours'
                                    THEN website_visitor.visit_count + 1
                                    ELSE website_visitor.visit_count
                                END
            RETURNING id, CASE WHEN create_date = now() at time zone 'UTC' THEN 'inserted' ELSE 'updated' END AS upsert
        , 'https://156611-17-0-all.runbot10.willdooit.net/shop/furn-6666-acoustic-bloc-screens-23' AS url, NULL AS page_id
                ), track AS (
                    INSERT INTO website_track (visitor_id, url, page_id, visit_datetime)
                    SELECT id, url, page_id::integer, now() at time zone 'UTC' FROM visitor
                )
                SELECT id, upsert from visitor;
ERROR: could not serialize access due to concurrent update