Hermo Soodla

I have turned on debug on my page to see errors. And if i run your plugin “Manual Cron Job Command” then i can see in debug log errors:
[17-Aug-2021 20:40:00 UTC] PHP Notice: Undefined index: sum_with in /home4/MYDOMAIN/public_html/wp-content/plugins/product-xml-feeds-for-woocommerce-pro/includes/shortcodes/class-alg-products-shortcodes.php on line 556.
But if i look *.xml file then i can not see update.

And anohter question:
What mean this /dev/null in end of command?
../admin-ajax.php?action=generate_xml_external&alg_create_products_xml=1 >/dev/null 2>&1