Slice selection returns 400 MANDATORY_IE_MISSING | AMF query lacks nf-type or nf-id | Confirm the AMF sends both mandatory query parameters |
Slice selection returns 400 "No slice info provided" | Query has none of slice-info-request-for-pdu-session, slice-info-request-for-registration, or snssai | Verify the AMF includes a slice-info object for the procedure |
Slice selection returns 403 SNSSAI_NOT_FOUND | Requested S-NSSAI has no matching NSI entry | Add the S-NSSAI to nsi_list (config) or via POST /oam/slice |
Response omits allowedNssaiList | No allowed_nssai entry for the query's PLMN and no home-PLMN fallback match | Add the PLMN (or home mcc-mnc) to allowed_nssai |
| Slice appears unavailable at a TAI | A conflicting AMF availability report exists for that TAI without the S-NSSAI | Inspect GET /api/nssai_availability; invalidate stale data with DELETE /oam/nssai_availability/{nfId} |
No targetAmfSet in response | No amf_set_mapping entry for the S-NSSAI key | Add the "sst-sd" key to amf_set_mapping |
NRF registration status 0 | NRF unreachable or wrong nrf_uri | Verify NRF_URI; force re-registration with POST /oam/nrf/reregister |
Availability PUT rejected 400 | Missing/empty supportedNssaiAvailabilityData, or an entry lacks tai or a non-empty supportedSnssaiList | Correct the AMF's availability body shape |
Availability PATCH returns 404 | JSON Patch sent for an nfId with no stored availability | PUT the availability first, or target the correct nfId |
Subscription creation rejected 400 | Body missing nfNssaiAvailabilityUri, taiList, or event | Supply all three required subscription fields |
Subscription PATCH/DELETE returns 404 | Unknown subscriptionId | Confirm the subscriptionId from the original Location header |
| Subscribers not notified | Callback nfNssaiAvailabilityUri unreachable | Notifications are retried with bounded backoff (nssf_notification_max_attempts attempts, default 3) before being dropped; check subscriber reachability and NSSF logs for the give-up warning |