A method for performing a service request procedure, by an access and mobility management function, AMF , in a wireless communication system, the method comprising: receiving , from an access network, AN, a request message for requesting a service to be used by a user equipment, UE ; transmitting , to a session management function, SMF, a first message comprising a PDU session ID associated with the service that is requested in the request message; and based on the SMF rejecting establishment of a User Plane of a PDU session for the service that is requested in the request message: receiving, from the SMF in response to the first message, a second message including a cause for the SMF rejecting the establishment of the User Plane of the PDU session; characterized in that the method further comprises: transmitting, to the UE , a response message for the failure of the PDU session, for response to the request message including a status of the PDU session in the AMF , based on the received second message including the cause, wherein the response message is transmitted after receiving the second message from all SMFs, based on multiple PDU sessions that involve multiple SMFs. receiving , from an access network, AN, a request message for requesting a service to be used by a user equipment, UE ; transmitting , to a session management function, SMF, a first message comprising a PDU session ID associated with the service that is requested in the request message; and based on the SMF rejecting establishment of a User Plane of a PDU session for the service that is requested in the request message: receiving, from the SMF in response to the first message, a second message including a cause for the SMF rejecting the establishment of the User Plane of the PDU session; characterized in that the method further comprises: transmitting, to the UE , a response message for the failure of the PDU session, for response to the request message including a status of the PDU session in the AMF , based on the received second message including the cause, wherein the response message is transmitted after receiving the second message from all SMFs, based on multiple PDU sessions that involve multiple SMFs. receiving, from the SMF in response to the first message, a second message including a cause for the SMF rejecting the establishment of the User Plane of the PDU session; characterized in that the method further comprises: transmitting, to the UE , a response message for the failure of the PDU session, for response to the request message including a status of the PDU session in the AMF , based on the received second message including the cause, wherein the response message is transmitted after receiving the second message from all SMFs, based on multiple PDU sessions that involve multiple SMFs. transmitting, to the UE , a response message for the failure of the PDU session, for response to the request message including a status of the PDU session in the AMF , based on the received second message including the cause, wherein the response message is transmitted after receiving the second message from all SMFs, based on multiple PDU sessions that involve multiple SMFs. <EOS>