Downgrade the device from v7.4.3 to v7.2.8 without active license and registration.

[Dattatray]

I have new device 401F. By default it is on the v7.4.3. I need to downgrade the device on the version 7.2.8. 

I tried to downgrade but getting an error "image downgrade failed. Failed to upgrade firmware due to expired firmware updates license." Is to possible to downgrade device without registration/activation of license. Also I verified with cli by using the command diag sys flash list only v7.4.3 is showing there.

[rtanagras · Accepted solution]

Hi @Dattatray - I think that's only possible if you format the device with a 7.2.8 image and manually convert the config file, or use the FortiConverter app to automatically handle the conversion.

Upgrading and downgrading have become more strict starting from version 7.4.2 and above. You can refer to this guide for more information about it: https://docs.fortinet.com/document/fortigate/7.4.3/administration-guide/299518/how-the-fortigate-fir...

"...For example, for FortiOS 7.4.x firmware upgrades, enforcement is based on the expiry date of the current support contract compared to the release date of FortiOS 7.4.0 GA.

Therefore, upgrades and downgrades between major, minor, and patch versions are only allowed if the firmware license is valid relative to the release date of the first GA release of a major version. If the firmware license expiry date is earlier than the firmware first GA major release date, then the firmware update to that version will not be allowed..."