AMF fails in Initial Context Setup when no SD is provisioned in the S-NSSAI delivered in NG Setup

[sysarch-repo]

2022-01-21T16:58:42Z [INFO][AMF][App] amf
2022-01-21T16:58:42Z [INFO][AMF][App] AMF version:
        free5GC version: v3.0.6
        build time:      2021-11-16T15:25:18Z
        commit hash:     b3e99f97
        commit time:     2021-09-24T09:44:32Z
        go version:      go1.14.4 linux/amd64

NG Setup:

bytes:
00150034000004001b00090099f999300000e0000052400a0380676e622d637563700066000d00000000010099f999000000080015400100

tAISliceSupportList: 1 item
    Item 0
        SliceSupportItem
            s-NSSAI
                sST: 01

AMF:
Fails to construct the Initial Context Setup Request

2022-01-21T16:48:27Z [DEBU][LIB][Aper] Encoding OpenType *ngapType.AllowedNSSAI to temp RawData (marshal.go:589) (/go/pkg/mod/github.com/free5gc/aper@v1.0.1/aper.go:24 github.com/free5gc/aper.perTrace)
2022-01-21T16:48:27Z [ERRO][AMF][NGAP][10.10.20.204:38412][AMF_UE_NGAP_ID:1] Build InitialContextSetupRequest failed : SEQUENCE OF Size is lower than lowerbound (/go/src/free5gc/NFs/amf/ngap/message/send.go:368 github.com/free5gc/amf/ngap/message.SendInitialContextSetupRequest)

after 6 sec the T3550 expires and the Registration Accept is retransmitted in a Downlink NAS Transport NGAP message.

2022-01-21T16:48:33Z [WARN][AMF][GMM][AMF_UE_NGAP_ID:1][SUPI:imsi-999990000000091] T3550 expires, retransmit Registration Accept (retry: 1) (/go/src/free5gc/NFs/amf/gmm/message/send.go:383 github.com/free5gc/amf/gmm/message.SendRegistrationAccept.func1)

With this, the UE is registered, but no Initial Context is set up.

Adding the SD in the NgSetup fixes the problem, but note, the SD in an optional parameter in the S-NSSAI.

[jorgenavarroortiz]

Do you have any update on this? SD should not be required as it is optional... Thanks.