A method of performing, by a user equipment, UE , a service request procedure in a wireless communication system, the method comprising: transmitting, via an access network, AN, to an access and mobility management function, AMF , a request message for requesting a service to be used by the UE , wherein the request message includes at least one PDU session ID; and receiving, via the AN from the AMF , a response message for the request message; wherein the response message for the request message includes information for a result of an establishment of at least one user plane resource for at least one PDU session related to the at least one PDU session ID, characterized in that based on i) the at least one PDU session being multiple PDU sessions that involve multiple Session Management Functions, SMFs, ii) an establishment of at least one user plane resource for at least one first PDU session of the multiple PDU sessions being accepted by at least one of the multiple SMFs and iii) an establishment of at least one user plane resource for at least one second PDU session of the multiple PDU sessions being rejected by at least one of the multiple SMFs: the response message for the request message is received from the AMF , after the AMF receives first messages from all of the multiple SMFs, at least one of the first messages includes a cause for the rejection of the establishment of the at least one user plane resource of the at least one second PDU session, and the response message for the request message includes information related to the cause for the rejection of the establishment of the at least one user plane resource of the at least one second PDU session. transmitting, via an access network, AN, to an access and mobility management function, AMF , a request message for requesting a service to be used by the UE , wherein the request message includes at least one PDU session ID; and receiving, via the AN from the AMF , a response message for the request message; wherein the response message for the request message includes information for a result of an establishment of at least one user plane resource for at least one PDU session related to the at least one PDU session ID, characterized in that based on i) the at least one PDU session being multiple PDU sessions that involve multiple Session Management Functions, SMFs, ii) an establishment of at least one user plane resource for at least one first PDU session of the multiple PDU sessions being accepted by at least one of the multiple SMFs and iii) an establishment of at least one user plane resource for at least one second PDU session of the multiple PDU sessions being rejected by at least one of the multiple SMFs: the response message for the request message is received from the AMF , after the AMF receives first messages from all of the multiple SMFs, at least one of the first messages includes a cause for the rejection of the establishment of the at least one user plane resource of the at least one second PDU session, and the response message for the request message includes information related to the cause for the rejection of the establishment of the at least one user plane resource of the at least one second PDU session. the response message for the request message is received from the AMF , after the AMF receives first messages from all of the multiple SMFs, at least one of the first messages includes a cause for the rejection of the establishment of the at least one user plane resource of the at least one second PDU session, and the response message for the request message includes information related to the cause for the rejection of the establishment of the at least one user plane resource of the at least one second PDU session. <EOS>