When trying to change domain id, the error message "%CONF-ERR: Invalid value" is returned. This article presents a way to change domain id on a circuit. An attempt to modify the domain for an already existing circuit returns the CLI error "Updating domain is not allowed" as shown below.
By default, when a new circuit is created, XOS assigns that circuit to domain 1. Optionally, you can use the domain parameter to assign a different domain to the circuit that you are configuring. It is not possible to update the domain of an already existing circuit.
To change domain for an existing circuit, you must remove the circuit and recreate it again with the desired domain value. Before removing the circuit, it is necessary to remove any existing references to that circuit in the CLI configuration (interface/group-interface, VRRP virtual router, or static routes).