Troubleshooting Tip: FortiGate incorrectly adding 'ffff' in the beginning of the FortiManager IP connector after upgrading to version 7.4.7

Users configure a Fortimanager in FortiGate for the central management settings.

config system central-management
    set type fortimanager
    set serial-number "FMG-VMxxxxxxx"
    set fmg "192.168.3.4"
    set fmg-source-ip 1.1.1.1

end

After upgrading to version  7.4.7, at the beginning of the FortiManager IP, the parameter 'ffff' gets added. 

config system central-management
    set type fortimanager
    set serial-number "FMG-VMxxxxxxx"
    set fmg "::ffff:192.168.3.4"
    set fmg-source-ip 1.1.1.1

end

This can cause FortiGate to change the source IP used for the communication. Run the following debugs to verify:

diagnose debug disable

diagnose debug reset
diagnose debug application fgfmd -1
diagnose debug console timestamp enable
diagnose debug enable

To stop debugging:

diagnose debug disable

In the debugs, it can be seen:

allow-push-firmware : enable
allow-remote-firmware-upgrade: enable
allow-monitor : enable
serial-number : "FMG-VMxxxxxxx"
fmg : "::ffff:192.168.3.4"
fmg-source-ip : 5.5.5.5 <- FortiGate uses an IP different from the one configured in the connector.
fmg-source-ip6 : ::

Workaround:

1. Delete the 'ffff' in the FortiManager IP through FortiGate GUI in the section 'Security Fabric - Fabric connector - Central management'.

Note: When trying to modify the IP through the CLI, FortiGate shows an error regarding the FortiManager Serial Number.

2. Restart the fgfmd process.

fnsysctl killall fgfmd

3. Refresh the FortiGate connector on the FortiManager side.

Fix schedule:

Upgrade to versions 7.4.8 and 7.6.1.