The disclosure relates to a fifth generation (5G) or sixth generation (6G) communication system for supporting a higher data transmission rate. A method performed by a user equipment (UE) for handling session management (SM) procedure in a wireless network system is provided. The method includes establishing, by the UE, a protocol data unit (PDU) session with a network apparatus in the wireless network system, determining, by the UE, whether the UE is in an area where a single-network slice selection assistance information (S-NSSAI) associated with the PDU session is not allowed or not supported by the network apparatus, and in case that the UE is in the area where the S-NSSAI of the PDU session is not allowed or not supported by the network apparatus, initiating, by the UE, a PDU session release procedure or initiating a PDU session modification procedure.