Update upgrade-from-23-04.md

versioned_docs/version-24.04/upgrade/upgrade-from-23-04.md

@@ -22,6 +22,8 @@ servers:
 - Central server
 - Database server
 
+If you use Open Ticket providers with custom configurations, [make a backup of these before updating Centreon](../alerts-notifications/ticketing-install.md#creating-a-backup-of-your-custom-open-ticket-provider-configurations).
+
 ## Upgrade the Centreon Central server
 
 > When you run a command, check its output. If you get an error message, stop the procedure and fix the issue.