FortiGate
FortiGate Next Generation Firewall utilizes purpose-built security processors and threat intelligence security services from FortiGuard labs to deliver top-rated protection and high performance, including encrypted traffic.
stymofiiev
Staff
Staff
Article Id 200604
Description

This article describes that there is a potential issue when customer tries to downgrade FortiGate 100F/101F Generation2. From the GUI it shows:

 'Image downgrade failed. Downgrading to the given image is not supported. Please burn the image from BIOS'.

 

If customer tries to upload the same firmware from tftp it will show:

 

FGT-100F/101F-Gen2 downgrades to version before 6.4.3 or 6.2.5 may result in the loss of some configuration, and unpredictable system performance.

 

Downgrading to the given image is not supported. Please burn the image from BIOS.
Check image error.
Command fail. Return code -28

 

Formatting boot device and uploading firmware following the clean install procedure described in:

 https://community.fortinet.com/t5/FortiGate/Technical-Tip-Loading-FortiGate-firmware-image-using-TFT...

externalID=FD47335 is also not recommended in this case as it may lead to unexpected results.

Scope FortiGate 100F, FortiGate 101F.
Solution

Use FortiOS 6.4.3 or 6.2.5 or above for FortiGate 100F/101F Gen2.

 

The quickest way to check is the unit Gen1 or Gen2 is to check the amount of builtin memory.

 

Gen1 has 4GB RAM and Gen2 has 8GB RAM.

 

It is also possible to check system part number in # get sys status output and verify if it's compatible using the following list:

 

https://docs.fortinet.com/document/fortigate/6.4.6/fortios-release-notes/884238/part-numbers-of-supp...

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