diff --git a/src/mme/emm_build.c b/src/mme/emm_build.c
index b3ba79dc1..3efb7f5f8 100644
--- a/src/mme/emm_build.c
+++ b/src/mme/emm_build.c
@@ -25,7 +25,6 @@ status_t emm_build_attach_accept(
         &attach_accept->eps_network_feature_support;
 
     d_assert(mme_ue, return CORE_ERROR, "Null param");
-    d_assert(mme_ue->enb_ue, return CORE_ERROR, "Null param");
     d_assert(esmbuf, return CORE_ERROR, "Null param");
 
     d_trace(3, "[EMM] Attach accept\n");
diff --git a/src/mme/mme_context.h b/src/mme/mme_context.h
index 22ba99a1d..9b1e5e626 100644
--- a/src/mme/mme_context.h
+++ b/src/mme/mme_context.h
@@ -304,10 +304,10 @@ struct _mme_ue_t {
     c_uint8_t       ebi; /* EPS Bearer ID generator */
     list_t          sess_list;
 
-#define ECM_IDLE(__mME) \
-    ((__mME) && ((__mME)->enb_ue == NULL))
 #define ECM_CONNECTED(__mME) \
-    ((__mME) && ((__mME)->enb_ue != NULL))
+    ((__mME) && ((__mME)->enb_ue != NULL) && \
+     enb_ue_find((__mME)->enb_ue->index))
+#define ECM_IDLE(__mME) (!ECM_CONNECTED(__mME))
     /* S1 UE context */
     enb_ue_t        *enb_ue;
 
diff --git a/src/mme/mme_sm.c b/src/mme/mme_sm.c
index 3ae5ba58e..752a83c7b 100644
--- a/src/mme/mme_sm.c
+++ b/src/mme/mme_sm.c
@@ -275,19 +275,9 @@ void mme_state_operational(fsm_t *s, event_t *e)
 
                 /* If NAS(mme_ue_t) has already been associated with
                  * older S1(enb_ue_t) context */
-                if (mme_ue->enb_ue)
+                if (ECM_CONNECTED(mme_ue))
                 {
-#if SEND_UE_CTX_REL_CMD_IMMEDIATELY
-                   /* Send UE context release command to 
-                    * older S1 context immediately. */
-                    d_trace(5, "OLD ENB_UE_S1AP_ID[%d] MME_UE_S1AP_ID[%d]\n",
-                        mme_ue->enb_ue->enb_ue_s1ap_id,
-                        mme_ue->enb_ue->mme_ue_s1ap_id);
-                    rv = s1ap_send_ue_context_release_command(mme_ue->enb_ue, 
-                            S1ap_Cause_PR_nas, S1ap_CauseNas_normal_release,
-                            S1AP_UE_CTX_REL_NO_ACTION, 0);
-                    d_assert(rv == CORE_OK, return, "s1ap send error");
-#elif IMPLICIT_S1_RELEASE
+#if IMPLICIT_S1_RELEASE
                    /* Implcit S1 release */
                     d_warn("Implicit S1 release");
                     d_warn("    ENB_UE_S1AP_ID[%d] MME_UE_S1AP_ID[%d]",
diff --git a/src/mme/s1ap_handler.c b/src/mme/s1ap_handler.c
index bcdfc262b..ead0fcc5e 100644
--- a/src/mme/s1ap_handler.c
+++ b/src/mme/s1ap_handler.c
@@ -161,19 +161,9 @@ void s1ap_handle_initial_ue_message(mme_enb_t *enb, s1ap_message_t *message)
 
                 /* If NAS(mme_ue_t) has already been associated with
                  * older S1(enb_ue_t) context */
-                if (mme_ue->enb_ue)
+                if (ECM_CONNECTED(mme_ue))
                 {
-#if SEND_UE_CTX_REL_CMD_IMMEDIATELY
-                   /* Send UE context release command to 
-                    * older S1 context immediately. */
-                    d_trace(5, "OLD ENB_UE_S1AP_ID[%d] MME_UE_S1AP_ID[%d]\n",
-                        mme_ue->enb_ue->enb_ue_s1ap_id,
-                        mme_ue->enb_ue->mme_ue_s1ap_id);
-                    rv = s1ap_send_ue_context_release_command(mme_ue->enb_ue, 
-                            S1ap_Cause_PR_nas, S1ap_CauseNas_normal_release,
-                            S1AP_UE_CTX_REL_NO_ACTION, 0);
-                    d_assert(rv == CORE_OK, return, "s1ap send error");
-#elif IMPLICIT_S1_RELEASE
+#if IMPLICIT_S1_RELEASE
                    /* Implcit S1 release */
                     d_warn("Implicit S1 release");
                     d_warn("    ENB_UE_S1AP_ID[%d] MME_UE_S1AP_ID[%d]",
@@ -563,7 +553,6 @@ void s1ap_handle_ue_context_release_request(
     enb_ue = enb_ue_find_by_mme_ue_s1ap_id(ies->mme_ue_s1ap_id);
     if (!enb_ue)
     {
-        d_assert(0,,);
         d_warn("No ENB UE Context : MME_UE_S1AP_ID[%d]", ies->mme_ue_s1ap_id);
         rv = s1ap_send_error_indication(enb, 
                 S1AP_ERRORINDICATIONIES_MME_UE_S1AP_ID_PRESENT |
diff --git a/test/attach_test.c b/test/attach_test.c
index 5f93512a9..5c219b46f 100644
--- a/test/attach_test.c
+++ b/test/attach_test.c
@@ -322,6 +322,12 @@ static void attach_test1(abts_case *tc, void *data)
     rv = tests1ap_enb_send(sock, sendbuf);
     ABTS_INT_EQUAL(tc, CORE_OK, rv);
 
+    /* Receive Error Indicaation */
+    recvbuf = pkbuf_alloc(0, MAX_SDU_LEN);
+    rv = tests1ap_enb_read(sock, recvbuf);
+    ABTS_INT_EQUAL(tc, CORE_OK, rv);
+    pkbuf_free(recvbuf);
+
 #else /* S1_HOLDING_TIMER */
     /* Send UE Context Release Request */
     rv = tests1ap_build_ue_context_release_request(&sendbuf, msgindex);