ZC 1.5.4, PHP 5.6, Zen Lightbox, Image Handler 4, Edit Orders, Easy Populate

I've got a ZenCart 1.5.4 install that is getting the following error:

[15-Nov-2020 10:42:59 America/New_York] PHP Fatal error: 1055:Expression #1 of ORDER BY clause is not in GROUP BY clause and contains nonaggregated column 'XXXXXX_##########.o.date_purchased' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by :: select p.products_id, p.products_image

from orders_products opa, orders_products opb, orders o, products p
where opa.products_id = '8933'
and opa.orders_id = opb.orders_id
and opb.products_id != '8933'
and opb.products_id = p.products_id
and opb.orders_id = o.orders_id
and p.products_status = 1
group by p.products_id
order by o.date_purchased desc
limit 6 ==> (as called by) /home/XXXXXX/public_html/XXXXXX/includes/modules/also_purchased_products.php on line 16 <== in /home/XXXXX/public_html/XXXXX/includes/classes/db/mysql/query_factory.php on line 155

Currently on my site when you run a search it just says "Warning: An Error occurred, please refresh the page and try again" When you open a product listing page the description, main image, and thumbnails load, then the same error message. Sidebars do not load. There could be other issues but haven't noticed yet. I got an order yesterday so appears site still is functioning to some extent.

If someone can give me a temp fix or advice for this issue would be grateful. This setup has served me well for past 6 years or so but I know it's way way past time to update to 1.5.7a and PHP 7.4 and plan on tackling this upgrade as well as moving to another host ASAP.

Thanks, Ted