Troubleshooting Tip: FortiExtender configuration gets removed while upgrading from FortiOS v7.0.17 to v7.4.8 on FortiGate-50G-DSL

When upgrading FortiGate-50G-DSL from FortiOS v7.0.17 to FortiOS v7.4.8, the FortiExtender configuration gets removed from FortiGate.

FortiGate-50G-DSL # diagnose debug config-error-log read
>>> "config" "extender-controller" "extender-profile" @ root:command parse error (error -61)
>>> "config" "extender-controller" "extender" @ root:command parse error (error -61)

FortiOS v7.0.17.

config extender-controller extender-profile
    edit "FX211E"
        set id 1
        set model FX211E
        set extension lan-extension
            config cellular
                config sms-notification
                end
                config modem1
                end
            end
            config lan-extension
                set ipsec-tunnel "fext-ipsec"
                set backhaul-interface "lan3"
                    config backhaul
                    edit "1"
                        set port wan
                        set role primary
                    next
                    edit "2"
                        set port lte1
                        set role secondary
                    next
            end
        end
    next
end

config extender-controller extender
    edit "FXxxxxxxxxxxxxx"
        set id "FXExxxxxxxxxxxxx"
        set authorized enable
        set device-id 1
        set extension-type wan-extension
            config wan-extension
                set modem1-extension "FEXT1"
            end
        set profile "FX211E"
    next
end

After upgrading to FortiOS v7.4.8, the FortiExtender gets removed on FortiGate-50G-DSL.

FortiGate-50G-DSL # show extension-controller extender
config extension-controller extender
end

FortiGate-50G-DSL # # show extension-controller extender-profile
config extension-controller extender-profile
end

The issue has been reported in internal Engineering ticket 1196352 and is resolved in FortiOS v7.4.9.

Related document:

Adding a FortiExtender