Troubleshooting Tip: Unable to unregister FortiGate from FortiManager with the error 'Please unregister-device from FortiManager first. -582'

[Umer221]

Description	This article describes how to fix an issue where, when trying to change the central management type from FortiManager to FortiGuard or none, administrators may run into an error that prevents them with the error 'Please unregister-device from FortiManager first. -582'.
Scope	FortiOS, FortiGate, FortiManager.
Solution	The error: config system central-management     set type none end Please unregister-device from FortiManager first. object set operator error, -582 discard the setting Command fail. Return code -582 A FortiManager serial number will be necessary to proceed further. Upon obtaining the serial number, run the following commands as shown in the photo: execute central-mgmt unregister-device <FortiManager serial number> To unregister the FortiGate from FortiCloud Manager when there is an FQDN instead of a serial number, use the following command.            execute central-mgmt unregister-device fortigatecloud.fortinet.com Finally, set the type to either 'FortiGuard' or 'none' using the following commands:   config system central-management     set type fortiguard <----- Alternatively, specify 'none'. end