Downgrading 40F - without losing configuration ?

[shlomim]

I'm running 40F with the latest version, it has FortiSwitch connected to it and managed by the 40F running the latest firmware as well, and 831F access points connected to the FortiSwitch, using the latest firmware managed by the 40F.

I understand that the recommended version is 7.2 and we're running 7.6

looking at the downgrade guides it says that the configuration would be saved.

is there a way to downgrade remotely without losing configuration ? or the only path is to downgrade and re-configure everything manually again ?

[atakannatak]

Hi @shlomim ,

Fortinet recommends different version depends on the hardware based on the below link. Versions in the 7.6 series are also supported by Fortinet. Yes, it maybe possible to downgrade a FortiGate without losing the configuration, if you follow the right process. However, there are risks and limitations, especially when moving from a higher major version (like 7.6) to a lower one (like 7.2), due to potential config syntax differences and features not supported in older versions. To retain configuration, you can manually edit the saved 7.6 config to fit 7.2 or use FortiConverter.

https://community.fortinet.com/t5/FortiGate/Technical-Tip-Recommended-Release-for-FortiOS/ta-p/22717...

First, back up the entire configuration, including FortiSwitch and AP configs, to ensure you can recover if necessary. After that there are two key points you should keep in mind:

1. During major version transitions (whether upgrading or downgrading), you may encounter issues such as configuration incompatibilities or syntax errors due to changes in the FortiOS architecture.
2. It’s essential to check the version compatibility of FortiSwitch and FortiAP devices. After a downgrade, FortiGate may not be able to function properly as a controller if there are version mismatches.

However, remote downgrades always carry risk—if something goes wrong during reboot, you may lose access—so it’s recommended to do this during a maintenance window and, if possible, have out-of-band access.

BR.

If my answer provided a solution for you, please mark the reply as solved it so that others can get it easily while searching for similar scenarios.

CCIE #68781

[AEK]

Currently the recommended FOS versions for FG-40F is 7.4.7.

https://community.fortinet.com/t5/FortiGate/Technical-Tip-Recommended-Release-for-FortiOS/ta-p/22717...

Regarding the downgrade, if you have a valid and up-to-date backup of your box when it was 7.4.x then just push the firmware and restore the config.

Otherwise know that a downgrade may lead to inconsistent configuration.