Quote Originally Posted by lat9 View Post
What's the site's setting for Configuration :: Logging :: Report All Errors (Admin)? If it's set to 'No', try setting it to 'IgnoreDups' and see if a log's generated.
Yep, that caught it. I installed the newsletter discount plugin, and that's where the problem is. Apparently it's looking to see whether this customer should have a price discount because of being a newsletter subscriber.

[26-Apr-2022 14:07:51 UTC] Request URI: /Zentest-CHAR-jasPe/index.php?cmd=edit_orders&page=1&oID=9989&action=update_order, IP address: 67.44.192.73
--> PHP Fatal error: Uncaught Error: Call to undefined function mailchimp_check() in /home/newnatur/zentest/includes/modules/order_total/ot_newsletter_discount.php:209
Stack trace:
#0 /home/newnatur/zentest/includes/modules/order_total/ot_newsletter_discount.php(44): ot_newsletter_discount->is_subscriber()
#1 /home/newnatur/zentest/includes/classes/order_total.php(65): ot_newsletter_discount->process()
#2 /home/newnatur/zentest/Zentest-CHAR-jasPe/includes/functions/extra_functions/edit_orders_functions.php(1431): order_total->process()
#3 /home/newnatur/zentest/Zentest-CHAR-jasPe/includes/modules/edit_orders/eo_update_order_action_processing.php(453): eo_update_database_order_totals(9989)
#4 /home/newnatur/zentest/Zentest-CHAR-jasPe/edit_orders.php(84): require('/home/newnatur/...')
#5 /home/newnatur/zentest/Zentest-CHAR-jasPe/index.php(11): require('/home/newnatur/...')
#6 {main}
thrown in /home/newnatur/zentest/includes/modules/order_total/ot_newsletter_discount.php on line 209.