A centralized unit (CU) for handling a handover for a user equipment (UE), executing instructions of: the CU receiving a Handover Request message from a base station (BS) for requesting a handover from the BS to the CU, wherein the Handover Request message comprises the first UE configuration; the CU sending a UE Context Setup Request message comprising the first UE configuration to a distributed unit (DU); the CU receiving a UE Context Setup Response message for responding to the UE Context Setup Request message from the DU, wherein the UE Context Setup Response message comprises a first full configuration indicator and a second UE configuration; and the CU sending a Handover Request Acknowledge message comprising a Radio Resource Control (RRC) message to the BS in response to the Handover Request message, wherein the RRC message comprises the second UE configuration and a second full configuration indicator.