The present document specifies the mapping: - performed by the AMF between HTTP responses (Status Codes and Protocol or Application Errors) returned by 5GC NFs to the AMF and 5GMM Cause values sent to UEs; - performed by the SMF between HTTP responses (Status Codes and Protocol or Application Errors) returned by 5GC NFs to SMF and 5GSM Cause values sent to UEs; - performed by the SMF between N4 errors returned by the UPF and 5GSM Cause values sent to UEs.