What is the best method to downgrade the version of Fireware OS on your Firebox without losing all device configuration settings?

Restoring a saved backup image created prior to the last upgrade is the best method to downgrade the version of Fireware OS while ensuring that all device configuration settings remain intact. When you create a backup image, it captures the entire configuration and current state of the Firebox at that specific time, allowing you to return to that configuration seamlessly during restoration. This process guarantees that settings, policies, and configurations will revert as they were when the backup was made, providing a complete and consistent setup without any loss or alteration of settings.

While using the Upgrade OS feature in Fireware Web UI may allow for an upgrade path, it does not support downgrading the OS. Changing the OS compatibility setting in Policy Manager typically impacts what policies and features are available but does not facilitate a downgrade of the Fireware OS itself. Utilizing the downgrade feature in Policy Manager may seem pertinent but often lacks the capability to maintain a comprehensive configuration state like a full backup restore does. Therefore, relying on a previous backup is the most effective and reliable choice to ensure both the OS version and settings are as desired upon downgrading.