diff --git a/src/smf/gsm-sm.c b/src/smf/gsm-sm.c
index d3d365666..81ccecbc9 100644
--- a/src/smf/gsm-sm.c
+++ b/src/smf/gsm-sm.c
@@ -1043,9 +1043,14 @@ void smf_gsm_state_operational(ogs_fsm_t *s, smf_event_t *e)
                 ogs_expect(r == OGS_OK);
                 ogs_assert(r != OGS_ERROR);
             } else {
-                ogs_error("[%s:%d] No PolicyAssociationId",
-                        smf_ue->supi, sess->psi);
-                OGS_FSM_TRAN(s, smf_gsm_state_exception);
+                ogs_warn("[%s:%d] No PolicyAssociationId. "
+                        "Forcibly remove SESSION", smf_ue->supi, sess->psi);
+                r = smf_sbi_discover_and_send(
+                        OGS_SBI_SERVICE_TYPE_NUDM_UECM, NULL,
+                        smf_nudm_uecm_build_deregistration, sess, stream,
+                        SMF_UECM_STATE_DEREGISTERED_BY_AMF, NULL);
+                ogs_expect(r == OGS_OK);
+                ogs_assert(r != OGS_ERROR);
             }
             break;
 
@@ -1516,6 +1521,9 @@ void smf_gsm_state_wait_5gc_n1_n2_release(ogs_fsm_t *s, smf_event_t *e)
             CASE(OGS_SBI_RESOURCE_NAME_MODIFY)
                 smf_nsmf_handle_update_sm_context(sess, stream, sbi_message);
                 break;
+            CASE(OGS_SBI_RESOURCE_NAME_RELEASE)
+                smf_nsmf_handle_release_sm_context(sess, stream, sbi_message);
+                break;
             DEFAULT
                 ogs_error("Invalid resource name [%s]",
                             sbi_message->h.resource.component[2]);
diff --git a/src/smf/nsmf-handler.c b/src/smf/nsmf-handler.c
index f248ec054..f9f9903b1 100644
--- a/src/smf/nsmf-handler.c
+++ b/src/smf/nsmf-handler.c
@@ -682,12 +682,14 @@ bool smf_nsmf_handle_update_sm_context(
             ogs_expect(r == OGS_OK);
             ogs_assert(r != OGS_ERROR);
         } else {
-            ogs_error("[%s:%d] No PolicyAssociationId. Forcibly remove SESSION",
+            ogs_warn("[%s:%d] No PolicyAssociationId. Forcibly remove SESSION",
                     smf_ue->supi, sess->psi);
-            smf_sbi_send_sm_context_update_error_log(
-                    stream, OGS_SBI_HTTP_STATUS_NOT_FOUND,
-                    "No PolicyAssociationId", NULL);
-            SMF_SESS_CLEAR(sess);
+            r = smf_sbi_discover_and_send(
+                    OGS_SBI_SERVICE_TYPE_NUDM_UECM, NULL,
+                    smf_nudm_uecm_build_deregistration, sess, stream,
+                    SMF_UECM_STATE_DEREGISTERED_BY_AMF, NULL);
+            ogs_expect(r == OGS_OK);
+            ogs_assert(r != OGS_ERROR);
         }
     } else if (SmContextUpdateData->serving_nf_id) {
         ogs_debug("Old serving_nf_id: %s, new serving_nf_id: %s",
@@ -779,13 +781,14 @@ bool smf_nsmf_handle_release_sm_context(
         ogs_expect(r == OGS_OK);
         ogs_assert(r != OGS_ERROR);
     } else {
-        ogs_error("[%s:%d] No PolicyAssociationId. Forcibly remove SESSION",
+        ogs_warn("[%s:%d] No PolicyAssociationId. Forcibly remove SESSION",
                 smf_ue->supi, sess->psi);
-        ogs_assert(true ==
-            ogs_sbi_server_send_error(
-                stream, OGS_SBI_HTTP_STATUS_NOT_FOUND,
-                NULL, "No PolicyAssociationId", NULL));
-        SMF_SESS_CLEAR(sess);
+        r = smf_sbi_discover_and_send(
+                OGS_SBI_SERVICE_TYPE_NUDM_UECM, NULL,
+                smf_nudm_uecm_build_deregistration, sess, stream,
+                SMF_UECM_STATE_DEREGISTERED_BY_AMF, NULL);
+        ogs_expect(r == OGS_OK);
+        ogs_assert(r != OGS_ERROR);
     }
 
     return true;
diff --git a/tests/vonr/session-test.c b/tests/vonr/session-test.c
index 25a334e34..a046f0ecd 100644
--- a/tests/vonr/session-test.c
+++ b/tests/vonr/session-test.c
@@ -2301,6 +2301,368 @@ static void test6_func(abts_case *tc, void *data)
     test_ue_remove(test_ue);
 }
 
+static void test7_func(abts_case *tc, void *data)
+{
+    int rv;
+    ogs_socknode_t *ngap;
+    ogs_socknode_t *gtpu;
+    ogs_pkbuf_t *gmmbuf;
+    ogs_pkbuf_t *gsmbuf;
+    ogs_pkbuf_t *nasbuf;
+    ogs_pkbuf_t *sendbuf;
+    ogs_pkbuf_t *recvbuf;
+    ogs_ngap_message_t message;
+    int i;
+
+    uint8_t tmp[OGS_HUGE_LEN];
+    char *_gtp_payload = "34ff0024"
+        "0000000100000085 010002004500001c 0c0b000040015a7a 0a2d00010a2d0002"
+        "00000964cd7c291f";
+
+    ogs_nas_5gs_mobile_identity_suci_t mobile_identity_suci;
+    test_ue_t *test_ue = NULL;
+    test_sess_t *sess5 = NULL, *sess6 = NULL;
+    test_bearer_t *qos_flow = NULL;
+
+    bson_t *doc = NULL;
+
+    /* Setup Test UE & Session Context */
+    memset(&mobile_identity_suci, 0, sizeof(mobile_identity_suci));
+
+    mobile_identity_suci.h.supi_format = OGS_NAS_5GS_SUPI_FORMAT_IMSI;
+    mobile_identity_suci.h.type = OGS_NAS_5GS_MOBILE_IDENTITY_SUCI;
+    mobile_identity_suci.routing_indicator1 = 0;
+    mobile_identity_suci.routing_indicator2 = 0xf;
+    mobile_identity_suci.routing_indicator3 = 0xf;
+    mobile_identity_suci.routing_indicator4 = 0xf;
+    mobile_identity_suci.protection_scheme_id = OGS_PROTECTION_SCHEME_NULL;
+    mobile_identity_suci.home_network_pki_value = 0;
+
+    test_ue = test_ue_add_by_suci(&mobile_identity_suci, "0000203190");
+    ogs_assert(test_ue);
+
+    test_ue->nr_cgi.cell_id = 0x40001;
+
+    test_ue->nas.registration.tsc = 0;
+    test_ue->nas.registration.ksi = OGS_NAS_KSI_NO_KEY_IS_AVAILABLE;
+    test_ue->nas.registration.follow_on_request = 1;
+    test_ue->nas.registration.value = OGS_NAS_5GS_REGISTRATION_TYPE_INITIAL;
+
+    test_ue->k_string = "465b5ce8b199b49faa5f0a2ee238a6bc";
+    test_ue->opc_string = "e8ed289deba952e4283b54e88e6183ca";
+
+    /* gNB connects to AMF */
+    ngap = testngap_client(AF_INET);
+    ABTS_PTR_NOTNULL(tc, ngap);
+
+    /* gNB connects to UPF */
+    gtpu = test_gtpu_server(1, AF_INET);
+    ABTS_PTR_NOTNULL(tc, gtpu);
+
+    /* Send NG-Setup Reqeust */
+    sendbuf = testngap_build_ng_setup_request(0x4000, 22);
+    ABTS_PTR_NOTNULL(tc, sendbuf);
+    rv = testgnb_ngap_send(ngap, sendbuf);
+    ABTS_INT_EQUAL(tc, OGS_OK, rv);
+
+    /* Receive NG-Setup Response */
+    recvbuf = testgnb_ngap_read(ngap);
+    ABTS_PTR_NOTNULL(tc, recvbuf);
+    testngap_recv(test_ue, recvbuf);
+
+    /********** Insert Subscriber in Database */
+    doc = test_db_new_ims(test_ue);
+    ABTS_PTR_NOTNULL(tc, doc);
+    ABTS_INT_EQUAL(tc, OGS_OK, test_db_insert_ue(test_ue, doc));
+
+    /* Send Registration request */
+    test_ue->registration_request_param.guti = 1;
+    gmmbuf = testgmm_build_registration_request(test_ue, NULL, false, false);
+    ABTS_PTR_NOTNULL(tc, gmmbuf);
+
+    test_ue->registration_request_param.gmm_capability = 1;
+    test_ue->registration_request_param.requested_nssai = 1;
+    test_ue->registration_request_param.last_visited_registered_tai = 1;
+    test_ue->registration_request_param.ue_usage_setting = 1;
+    nasbuf = testgmm_build_registration_request(test_ue, NULL, false, false);
+    ABTS_PTR_NOTNULL(tc, nasbuf);
+
+    sendbuf = testngap_build_initial_ue_message(test_ue, gmmbuf,
+                NGAP_RRCEstablishmentCause_mo_Signalling, false, true);
+    ABTS_PTR_NOTNULL(tc, sendbuf);
+    rv = testgnb_ngap_send(ngap, sendbuf);
+    ABTS_INT_EQUAL(tc, OGS_OK, rv);
+
+    /* Receive Identity request */
+    recvbuf = testgnb_ngap_read(ngap);
+    ABTS_PTR_NOTNULL(tc, recvbuf);
+    testngap_recv(test_ue, recvbuf);
+
+    /* Send Identity response */
+    gmmbuf = testgmm_build_identity_response(test_ue);
+    ABTS_PTR_NOTNULL(tc, gmmbuf);
+    sendbuf = testngap_build_uplink_nas_transport(test_ue, gmmbuf);
+    ABTS_PTR_NOTNULL(tc, sendbuf);
+    rv = testgnb_ngap_send(ngap, sendbuf);
+    ABTS_INT_EQUAL(tc, OGS_OK, rv);
+
+    /* Receive Authentication request */
+    recvbuf = testgnb_ngap_read(ngap);
+    ABTS_PTR_NOTNULL(tc, recvbuf);
+    testngap_recv(test_ue, recvbuf);
+
+    /* Send Authentication response */
+    gmmbuf = testgmm_build_authentication_response(test_ue);
+    ABTS_PTR_NOTNULL(tc, gmmbuf);
+    sendbuf = testngap_build_uplink_nas_transport(test_ue, gmmbuf);
+    ABTS_PTR_NOTNULL(tc, sendbuf);
+    rv = testgnb_ngap_send(ngap, sendbuf);
+    ABTS_INT_EQUAL(tc, OGS_OK, rv);
+
+    /* Receive Security mode command */
+    recvbuf = testgnb_ngap_read(ngap);
+    ABTS_PTR_NOTNULL(tc, recvbuf);
+    testngap_recv(test_ue, recvbuf);
+
+    /* Send Security mode complete */
+    gmmbuf = testgmm_build_security_mode_complete(test_ue, nasbuf);
+    ABTS_PTR_NOTNULL(tc, gmmbuf);
+    sendbuf = testngap_build_uplink_nas_transport(test_ue, gmmbuf);
+    ABTS_PTR_NOTNULL(tc, sendbuf);
+    rv = testgnb_ngap_send(ngap, sendbuf);
+    ABTS_INT_EQUAL(tc, OGS_OK, rv);
+
+    /* Receive InitialContextSetupRequest +
+     * Registration accept */
+    recvbuf = testgnb_ngap_read(ngap);
+    ABTS_PTR_NOTNULL(tc, recvbuf);
+    testngap_recv(test_ue, recvbuf);
+    ABTS_INT_EQUAL(tc,
+            NGAP_ProcedureCode_id_InitialContextSetup,
+            test_ue->ngap_procedure_code);
+
+    /* Send UERadioCapabilityInfoIndication */
+    sendbuf = testngap_build_ue_radio_capability_info_indication(test_ue);
+    ABTS_PTR_NOTNULL(tc, sendbuf);
+    rv = testgnb_ngap_send(ngap, sendbuf);
+    ABTS_INT_EQUAL(tc, OGS_OK, rv);
+
+    /* Send InitialContextSetupResponse */
+    sendbuf = testngap_build_initial_context_setup_response(test_ue, false);
+    ABTS_PTR_NOTNULL(tc, sendbuf);
+    rv = testgnb_ngap_send(ngap, sendbuf);
+    ABTS_INT_EQUAL(tc, OGS_OK, rv);
+
+    /* Send Registration complete */
+    gmmbuf = testgmm_build_registration_complete(test_ue);
+    ABTS_PTR_NOTNULL(tc, gmmbuf);
+    sendbuf = testngap_build_uplink_nas_transport(test_ue, gmmbuf);
+    ABTS_PTR_NOTNULL(tc, sendbuf);
+    rv = testgnb_ngap_send(ngap, sendbuf);
+    ABTS_INT_EQUAL(tc, OGS_OK, rv);
+
+    /* Receive Configuration update command */
+    recvbuf = testgnb_ngap_read(ngap);
+    ABTS_PTR_NOTNULL(tc, recvbuf);
+    testngap_recv(test_ue, recvbuf);
+
+    /* Send PDU session establishment request */
+    sess5 = test_sess_add_by_dnn_and_psi(test_ue, "internet", 5);
+    ogs_assert(sess5);
+
+    sess5->ul_nas_transport_param.request_type =
+        OGS_NAS_5GS_REQUEST_TYPE_INITIAL;
+    sess5->ul_nas_transport_param.dnn = 1;
+    sess5->ul_nas_transport_param.s_nssai = 1;
+
+    sess5->pdu_session_establishment_param.ssc_mode = 1;
+    sess5->pdu_session_establishment_param.epco = 1;
+
+    gsmbuf = testgsm_build_pdu_session_establishment_request(sess5);
+    ABTS_PTR_NOTNULL(tc, gsmbuf);
+    gmmbuf = testgmm_build_ul_nas_transport(sess5,
+            OGS_NAS_PAYLOAD_CONTAINER_N1_SM_INFORMATION, gsmbuf);
+    ABTS_PTR_NOTNULL(tc, gmmbuf);
+    sendbuf = testngap_build_uplink_nas_transport(test_ue, gmmbuf);
+    ABTS_PTR_NOTNULL(tc, sendbuf);
+    rv = testgnb_ngap_send(ngap, sendbuf);
+    ABTS_INT_EQUAL(tc, OGS_OK, rv);
+
+    /* Receive PDUSessionResourceSetupRequest +
+     * DL NAS transport +
+     * PDU session establishment accept */
+    recvbuf = testgnb_ngap_read(ngap);
+    ABTS_PTR_NOTNULL(tc, recvbuf);
+    testngap_recv(test_ue, recvbuf);
+    ABTS_INT_EQUAL(tc,
+            NGAP_ProcedureCode_id_PDUSessionResourceSetup,
+            test_ue->ngap_procedure_code);
+
+    /* Send PDUSessionResourceSetupResponse */
+    sendbuf = testngap_sess_build_pdu_session_resource_setup_response(sess5);
+    ABTS_PTR_NOTNULL(tc, sendbuf);
+    rv = testgnb_ngap_send(ngap, sendbuf);
+    ABTS_INT_EQUAL(tc, OGS_OK, rv);
+
+    /* Send PDU session establishment request */
+    sess6 = test_sess_add_by_dnn_and_psi(test_ue, "ims", 6);
+    ogs_assert(sess6);
+
+    sess6->ul_nas_transport_param.request_type =
+        OGS_NAS_5GS_REQUEST_TYPE_INITIAL;
+    sess6->ul_nas_transport_param.dnn = 1;
+    sess6->ul_nas_transport_param.s_nssai = 1;
+
+    sess6->pdu_session_establishment_param.ssc_mode = 1;
+    sess6->pdu_session_establishment_param.epco = 1;
+
+    gsmbuf = testgsm_build_pdu_session_establishment_request(sess6);
+    ABTS_PTR_NOTNULL(tc, gsmbuf);
+    gmmbuf = testgmm_build_ul_nas_transport(sess6,
+            OGS_NAS_PAYLOAD_CONTAINER_N1_SM_INFORMATION, gsmbuf);
+    ABTS_PTR_NOTNULL(tc, gmmbuf);
+    sendbuf = testngap_build_uplink_nas_transport(test_ue, gmmbuf);
+    ABTS_PTR_NOTNULL(tc, sendbuf);
+    rv = testgnb_ngap_send(ngap, sendbuf);
+    ABTS_INT_EQUAL(tc, OGS_OK, rv);
+
+    /* Receive PDU sess6ion establishment accept */
+    recvbuf = testgnb_ngap_read(ngap);
+    ABTS_PTR_NOTNULL(tc, recvbuf);
+    testngap_recv(test_ue, recvbuf);
+
+    /* Send PDUSessionResourceSetupResponse */
+    sendbuf = testngap_sess_build_pdu_session_resource_setup_response(sess6);
+    ABTS_PTR_NOTNULL(tc, sendbuf);
+    rv = testgnb_ngap_send(ngap, sendbuf);
+    ABTS_INT_EQUAL(tc, OGS_OK, rv);
+
+    /* Send PDU Session release request */
+    sess6->pti = 38;
+    sess6->ul_nas_transport_param.request_type = 0;
+    sess6->ul_nas_transport_param.dnn = 0;
+    sess6->ul_nas_transport_param.s_nssai = 0;
+
+    sess6->pdu_session_establishment_param.ssc_mode = 0;
+    sess6->pdu_session_establishment_param.epco = 0;
+
+    gsmbuf = testgsm_build_pdu_session_release_request(sess6);
+    ABTS_PTR_NOTNULL(tc, gsmbuf);
+    gmmbuf = testgmm_build_ul_nas_transport(sess6,
+            OGS_NAS_PAYLOAD_CONTAINER_N1_SM_INFORMATION, gsmbuf);
+    ABTS_PTR_NOTNULL(tc, gmmbuf);
+    sendbuf = testngap_build_uplink_nas_transport(test_ue, gmmbuf);
+    ABTS_PTR_NOTNULL(tc, sendbuf);
+    rv = testgnb_ngap_send(ngap, sendbuf);
+    ABTS_INT_EQUAL(tc, OGS_OK, rv);
+
+    /* Send PDU Session release request */
+    sess5->pti = 39;
+    sess5->ul_nas_transport_param.request_type = 0;
+    sess5->ul_nas_transport_param.dnn = 0;
+    sess5->ul_nas_transport_param.s_nssai = 0;
+
+    sess5->pdu_session_establishment_param.ssc_mode = 0;
+    sess5->pdu_session_establishment_param.epco = 0;
+
+    gsmbuf = testgsm_build_pdu_session_release_request(sess5);
+    ABTS_PTR_NOTNULL(tc, gsmbuf);
+    gmmbuf = testgmm_build_ul_nas_transport(sess5,
+            OGS_NAS_PAYLOAD_CONTAINER_N1_SM_INFORMATION, gsmbuf);
+    ABTS_PTR_NOTNULL(tc, gmmbuf);
+    sendbuf = testngap_build_uplink_nas_transport(test_ue, gmmbuf);
+    ABTS_PTR_NOTNULL(tc, sendbuf);
+    rv = testgnb_ngap_send(ngap, sendbuf);
+    ABTS_INT_EQUAL(tc, OGS_OK, rv);
+
+    /* Receive PDUSessionResourceReleaseCommand +
+     * DL NAS transport +
+     * PDU session release command */
+    recvbuf = testgnb_ngap_read(ngap);
+    ABTS_PTR_NOTNULL(tc, recvbuf);
+    testngap_recv(test_ue, recvbuf);
+    ABTS_INT_EQUAL(tc,
+            NGAP_ProcedureCode_id_PDUSessionResourceRelease,
+            test_ue->ngap_procedure_code);
+
+    /* Receive PDUSessionResourceReleaseCommand +
+     * DL NAS transport +
+     * PDU session release command */
+    recvbuf = testgnb_ngap_read(ngap);
+    ABTS_PTR_NOTNULL(tc, recvbuf);
+    testngap_recv(test_ue, recvbuf);
+    ABTS_INT_EQUAL(tc,
+            NGAP_ProcedureCode_id_PDUSessionResourceRelease,
+            test_ue->ngap_procedure_code);
+
+    /* Send PDUSessionResourceReleaseResponse */
+    sendbuf = testngap_build_pdu_session_resource_release_response(sess6);
+    ABTS_PTR_NOTNULL(tc, sendbuf);
+    rv = testgnb_ngap_send(ngap, sendbuf);
+    ABTS_INT_EQUAL(tc, OGS_OK, rv);
+
+    /* Send UplinkNASTransport +
+     * UL NAS trasnport +
+     * PDU session resource release complete */
+    sess6->ul_nas_transport_param.request_type = 0;
+    sess6->ul_nas_transport_param.dnn = 0;
+    sess6->ul_nas_transport_param.s_nssai = 0;
+
+    sess6->pdu_session_establishment_param.ssc_mode = 0;
+    sess6->pdu_session_establishment_param.epco = 0;
+
+    gsmbuf = testgsm_build_pdu_session_release_complete(sess6);
+    ABTS_PTR_NOTNULL(tc, gsmbuf);
+    gmmbuf = testgmm_build_ul_nas_transport(sess6,
+            OGS_NAS_PAYLOAD_CONTAINER_N1_SM_INFORMATION, gsmbuf);
+    ABTS_PTR_NOTNULL(tc, gmmbuf);
+    sendbuf = testngap_build_uplink_nas_transport(test_ue, gmmbuf);
+    ABTS_PTR_NOTNULL(tc, sendbuf);
+    rv = testgnb_ngap_send(ngap, sendbuf);
+    ABTS_INT_EQUAL(tc, OGS_OK, rv);
+
+    /* Test Session Remove */
+    test_sess_remove(sess6);
+
+    ogs_msleep(100);
+
+    /* Send De-registration request */
+    gmmbuf = testgmm_build_de_registration_request(test_ue, 1, true, true);
+    ABTS_PTR_NOTNULL(tc, gmmbuf);
+    sendbuf = testngap_build_uplink_nas_transport(test_ue, gmmbuf);
+    ABTS_PTR_NOTNULL(tc, sendbuf);
+    rv = testgnb_ngap_send(ngap, sendbuf);
+    ABTS_INT_EQUAL(tc, OGS_OK, rv);
+
+    /* Receive UEContextReleaseCommand */
+    recvbuf = testgnb_ngap_read(ngap);
+    ABTS_PTR_NOTNULL(tc, recvbuf);
+    testngap_recv(test_ue, recvbuf);
+    ABTS_INT_EQUAL(tc,
+            NGAP_ProcedureCode_id_UEContextRelease,
+            test_ue->ngap_procedure_code);
+
+    /* Send UEContextReleaseComplete */
+    sendbuf = testngap_build_ue_context_release_complete(test_ue);
+    ABTS_PTR_NOTNULL(tc, sendbuf);
+    rv = testgnb_ngap_send(ngap, sendbuf);
+    ABTS_INT_EQUAL(tc, OGS_OK, rv);
+
+    ogs_msleep(300);
+
+    /********** Remove Subscriber in Database */
+    ABTS_INT_EQUAL(tc, OGS_OK, test_db_remove_ue(test_ue));
+
+    /* gNB disonncect from UPF */
+    testgnb_gtpu_close(gtpu);
+
+    /* gNB disonncect from AMF */
+    testgnb_ngap_close(ngap);
+
+    /* Clear Test UE Context */
+    test_ue_remove(test_ue);
+}
+
 abts_suite *test_session(abts_suite *suite)
 {
     suite = ADD_SUITE(suite)
@@ -2311,6 +2673,7 @@ abts_suite *test_session(abts_suite *suite)
     abts_run_test(suite, test4_func, NULL);
     abts_run_test(suite, test5_func, NULL);
     abts_run_test(suite, test6_func, NULL);
+    abts_run_test(suite, test7_func, NULL);
 
     return suite;
 }