Although it is expected that the upgrade procedure will progress and complete without any problems, you should have a contingency plan to back out or restore the previous state of operations.

Both Core and Edge upgrade procedures automatically install the new software image into a backup partition on the appliance. The existing (running) software image is in a separate (active) partition. During the reboot, which is part of the upgrade procedure, the roles of the backup and active partitions are reversed. This action ensures that if you require a downgrade to restore the previous software version, a partition swap and reboot are all that should be required.

If you have a lab or development environment in which some nonproduction appliances are in use, consider doing a trial upgrade. This upgrade ensures you have some exposure to the upgrade processes, enables you to measure the time taken to perform the tasks, and gain other useful experience. You can complete the trial upgrade well ahead of the production upgrade to confirm the new version of software operates as expected.