Before reverting an ONTAP cluster to a previous version, you must resolve any incompatibilities introduced by the new software.

1. Deleting recent Snapshot copies (B) is a mandatory prerequisite. Snapshot copies created with a newer ONTAP version (9.7) may contain metadata or use formats not understood by the older version (9.5). The revert pre-check will fail if these snapshots exist.

2. Addressing incompatible features (D) is also required. If a feature was enabled in ONTAP 9.7 that is irreversible and incompatible with 9.5, the revert is blocked. In such a severe case, simply disabling the feature is not possible. The only way to proceed is to remove the incompatible configuration, which may necessitate wiping the configuration and restoring from a backup created when the cluster was running the target version (9.5).

A. Revert from ONTAP 9.7 software to ONTAP 9.6 software and then to ONTAP 9.5 software.

This is procedurally incorrect. The system image revert command returns the node to the single, previously installed software image stored on the alternate boot partition, not through intermediate versions.

C. Reinstall your boot media and install ONTAP 9.5 software.

This describes a clean installation or re-imaging of a node, which is a different and more disruptive procedure than a standard revert that uses the existing alternate boot image.

1. NetApp ONTAP 9.7, Upgrade and Revert/Downgrade Guide, Section: "Reverting to a previous version of ONTAP", Page 33.

This guide explicitly lists as a prerequisite: "You must delete any Snapshot copies that were created after the software update." This directly validates option B.

The guide also states: "You must have reverted or disabled any features that are not supported in the target release... If you cannot revert a feature, you might have to remove the configuration for that feature before you can revert the software." This supports the logic for option D as the necessary action for an irreversible feature configuration.

2. NetApp ONTAP 9, System Administration Guide, Section: "Overview of cluster configuration backup and restore".

This documentation outlines the procedure for backing up and restoring cluster configuration. It describes restoring a configuration as a method to return to a previous known-good state, which would be required if a revert is blocked by an incompatible configuration that cannot be manually removed, thus validating the scenario in option D.