In a first novel aspect, UE receives a mapped EPS bearer context IE during a PDU session establishment or modification procedure. UE diagnoses whether an operation error occurs for a mapped EPS bearer context. If so, UE deletes the mapped EPS bearer context with a 5GSM cause. In a second novel aspect, UE receives a QoS flow description IE during a PDU session establishment or modification procedure. UE diagnoses whether an operation error occurs for a QoS flow description. If so, UE either rejects the modification command or deletes the QoS flow description with a 5GSM cause. In a third novel aspect, UE receives a QoS flow description IE during an EPS bearer activation or modification procedure. UE diagnoses whether an operation error occurs for a QoS flow description. If so, UE includes an ePCO/PCO IE with a 5GSM cause in an activation or modification accept message.