Troubleshooting Tip: The FortiExtender could not be authorized on the FortiGate GUI due to error 'Empty values are not allowed'

The FortiGate GUI may present the following errors when the User tries to authorize the FortiExtender:

'The following devices could not be authorized.'

'Empty values are not allowed.'

1. This is a known issue on FortiOS, and the fix is now available in the new FortiOS v7.4.8 GA.

See 1114549: Authorization of FEXT devices fails when using the FortiGate GUI - FortiGate resolved issues.

2. Alternatively, if the FortiGate firmware upgrade is not possible, as a temporary workaround, the User can authorize the FortiExtender via FortiGate CLI commands as shown below:

config extension-controller extender
    edit "FXW51GSXXXXXXXXX"
        set id "FXW51GSXXXXXXXXX"
        set authorized enable              <----- Ensure the authorized command is enabled.
        set device-id 0
        set extension-type wan-extension
        set profile "FXW51G-wanext-default"
            config wan-extension
                set modem1-extension "<interface_name>"        <----- Ensure modem1-extension interface name is mapped.
            end
        next
    end

Note: The same command can be used to authorize FortiExtender in the 'lan-extension' or 'wan-extension' modes.

Related documents:

• Provision FortiExtender firmware upon authorization - FortiExtender 7.6.2 administration guide
• FortiExtender and FortiGate integration - FortiExtender 7.6.2 administration guide