FortiManager Firmware : Downgrading to previous firmware versions
 
Downgrading to previous firmware versions
FortiManager does not provide a full downgrade path. You can downgrade to a previous FortiManager firmware release via the Web-based Manager or CLI. A system reset is required after the firmware downgrading process has completed.
 
All configuration will be lost after downgrading the device. For FortiManager devices with hard drives installed, the hard drives will be formatted.
To re-initialize a FortiManager use the following CLI commands via a console port connection:
execute reset all-settings
execute format {disk | disk-ext4}