Technical Tip: How to identify and restore previous version of firmware

[rameshk_FTNT]

Description

This article provides a method to identify and, if necessary, to restore previous firmware image from a flash disk (downgrade to previous version).

The relevant Release Notes and Admin Guides should be consulted before any firmware version changes to understand the implications of the change.

Scope

Identify previous firmware version.
Restore previous firmware version.

Solution

The following example illustrates how to restore the firmware from v7.0.6 to v6.4.9.

1. Determine the Image revision ID on flash using the command:
   
   diag sys flash list
   
   
   Use the build number to determine the precise firmware version and compare it to support.fortinet.com or the upgrade tool, which allows one to confirm which build number corresponds to the firmware version.

An alternative way to confirm the firmware version would be from the backup config, the first line consists of the firmware version along with the build number such as '#config-version=FGT-7.0.15-FW-build0632-240403:opmode=0:vdom=0:'.

2.  Use the following command to restore the firmware held in partition 2:
   

The device will reboot and load the previously selected version.