What can you expect during the upgrade? The upgrade generally take less than ten minutes, but may take longer if you have a lot of files or a complex setup. During this time, Oracle Integration Generation 2 is unavailable.

1. On the day of the upgrade: Make sure everyone stops work in Oracle Integration Generation 2 before the beginning of the upgrade window.
2. When the upgrade begins: Oracle sends an email when the upgrade begins. By default, upgrade notifications are automatically sent to the specified administrator email. Oracle recommends you have notifications sent to a distribution list or group email so that you don't miss important emails if someone leaves the company. You set who receives notifications on the Upgrade page. See "Upgrade Notifications" in Configure Your Upgrade Settings.
3. Wait for the upgrade to complete: If you sign in during the downtime, a message appears, indicating that the instance is temporarily unavailable.
   During the downtime, Oracle completes the following tasks:

   1. Checks to make sure that the instance is still ready for upgrade.

      For example, you might begin using a deprecated feature after your instance passes the upgrade check. In such a case, your instance is no longer ready for upgrade. Oracle emails you to inform you that everyone will continue working in the Oracle Integration Generation 2 and provides the next steps.

   2. Stops the scheduled integrations in the Oracle Integration Generation 2 instance.
   3. Stops all activity, including design time and runtime, in the instance.

      If a scheduled integration is running in Oracle Integration Generation 2, the integration starts where it left off in Oracle Integration 3.

   4. Moves data to the new instance.

      The data that is moved includes integrations, connections, packages, certificates, settings, and other metadata, plus in-flight instance data. See How Upgrade Affects Runtime Data.

   5. Updates the hostname of the Oracle Integration Generation 2 instance.

      The hostname points to the new Oracle Integration 3 instance. This change ensures that requests are sent to your new Oracle Integration 3 instance after the upgrade.

   6. Creates a mapping between the Oracle Identity Cloud Service and the new instance.

      This mapping ensures that security-related information from your Oracle Integration Generation 2 instance is present in your Oracle Integration 3 instance.

   7. Starts the scheduled integrations in the Oracle Integration 3 instance.

   Note
   
   For integrations that use three-legged OAuth 2.0, the redirect URIs that you specified for client applications do not change after upgrade, even though your instance gets a new URL. Additionally, when you need to register a new client application after the upgrade is complete, you must use the Oracle Integration Generation 2 redirect URI.
4. After the upgrade finishes: The Oracle Integration 3 instance starts processing all requests, and Oracle sends an email saying that the upgrade is complete.
   Note
   
   In rare situations, an issue prevents an upgrade from completing. When an upgrade doesn't complete, Oracle rolls back the changes, turns on the schedule in the Oracle Integration Generation 2 instance, and restores your access to the instance during the downtime period. You continue working in the Oracle Integration Generation 2 instance, with the same features you were using before the upgrade.

   In such situations, Oracle sends an email that you can continue working in Oracle Integration Generation 2. Expect the email to arrive either within your upgrade window or soon after. You can schedule your upgrade for another time, and Oracle works with you to determine the next steps.

5. After you get the email saying the upgrade is complete, complete the post-upgrade tasks.