Older versions of the M1 Extension are no longer supported and are likely to cause "
fail-order" errors within the new app. Please check that your extension version matches the latest version available (https://github.com/zendesk/magento_extension). If not please update by following the instructions in Magento: Installing the Zendesk extension for Magento.
Errors caused by outdated M1 Extension versions can be seen within your Magento PHP logs, and include the following error messages:
Uncaught exception ‘ArgumentCountError’ with message ‘Too few arguments to function ZendeskZendeskApiController::ordersAction()
PHP Fatal error: Call to a member function find() on a non-object in /var/www/html/apache.git/magento/store2/app/code/community/Zendesk/Zendesk/Model/Observer.php`
If you have a firewall in front of your Magento instance (and/or CDN), ensure you have allowed Zendesk’s IPs for the secure proxy mentioned previously access your M1 Extension. For more details, see Configuring your firewall for Zendesk.