diff --git a/src/mme/mme-context.c b/src/mme/mme-context.c
index ef41b5edc..14f9c8582 100644
--- a/src/mme/mme-context.c
+++ b/src/mme/mme-context.c
@@ -1942,7 +1942,11 @@ enb_ue_t *enb_ue_add(mme_enb_t *enb, uint32_t enb_ue_s1ap_id)
     ogs_assert(enb);
 
     ogs_pool_alloc(&enb_ue_pool, &enb_ue);
-    ogs_assert(enb_ue);
+    if (enb_ue == NULL) {
+        ogs_error("Could not allocate enb_ue context from pool");
+        return NULL;
+    }
+
     memset(enb_ue, 0, sizeof *enb_ue);
 
     enb_ue->t_s1_holding = ogs_timer_add(
@@ -2266,7 +2270,11 @@ mme_ue_t *mme_ue_add(enb_ue_t *enb_ue)
     ogs_assert(enb);
 
     ogs_pool_alloc(&mme_ue_pool, &mme_ue);
-    ogs_assert(mme_ue);
+    if (mme_ue == NULL) {
+        ogs_error("Could not allocate mme_ue context from pool");
+        return NULL;
+    }
+
     memset(mme_ue, 0, sizeof *mme_ue);
 
     /* Add All Timers */
diff --git a/src/mme/mme-sm.c b/src/mme/mme-sm.c
index 259623c20..c725a4dfd 100644
--- a/src/mme/mme-sm.c
+++ b/src/mme/mme-sm.c
@@ -250,7 +250,15 @@ void mme_state_operational(ogs_fsm_t *s, mme_event_t *e)
             mme_ue = mme_ue_find_by_message(&nas_message);
             if (!mme_ue) {
                 mme_ue = mme_ue_add(enb_ue);
-                ogs_assert(mme_ue);
+                if (mme_ue == NULL) {
+                    ogs_expect(OGS_OK ==
+                        s1ap_send_ue_context_release_command(enb_ue,
+                            S1AP_Cause_PR_misc,
+                            S1AP_CauseMisc_control_processing_overload,
+                            S1AP_UE_CTX_REL_S1_CONTEXT_REMOVE, 0));
+                    ogs_pkbuf_free(pkbuf);
+                    return;
+                }
             } else {
                 /* Here, if the MME_UE Context is found,
                  * the integrity check is not performed
diff --git a/src/mme/s1ap-handler.c b/src/mme/s1ap-handler.c
index 683159340..530126f4d 100644
--- a/src/mme/s1ap-handler.c
+++ b/src/mme/s1ap-handler.c
@@ -258,7 +258,13 @@ void s1ap_handle_initial_ue_message(mme_enb_t *enb, ogs_s1ap_message_t *message)
     enb_ue = enb_ue_find_by_enb_ue_s1ap_id(enb, *ENB_UE_S1AP_ID);
     if (!enb_ue) {
         enb_ue = enb_ue_add(enb, *ENB_UE_S1AP_ID);
-        ogs_assert(enb_ue);
+        if (enb_ue == NULL) {
+            ogs_assert(OGS_OK ==
+                s1ap_send_error_indication(enb, NULL, NULL,
+                    S1AP_Cause_PR_misc,
+                    S1AP_CauseMisc_control_processing_overload));
+            return;
+        }
 
         /* Find MME_UE if S_TMSI included */
         if (S_TMSI) {
diff --git a/src/mme/s1ap-path.c b/src/mme/s1ap-path.c
index eb9075fa0..4e3a18d39 100644
--- a/src/mme/s1ap-path.c
+++ b/src/mme/s1ap-path.c
@@ -515,7 +515,13 @@ int s1ap_send_handover_request(
     ogs_assert(target_enb);
 
     target_ue = enb_ue_add(target_enb, INVALID_UE_S1AP_ID);
-    ogs_assert(target_ue);
+    if (target_ue == NULL) {
+        ogs_assert(OGS_OK ==
+            s1ap_send_error_indication(target_enb, NULL, NULL,
+                S1AP_Cause_PR_misc,
+                S1AP_CauseMisc_control_processing_overload));
+        return OGS_ERROR;
+    }
 
     ogs_info("    Source : ENB_UE_S1AP_ID[%d] MME_UE_S1AP_ID[%d]",
             source_ue->enb_ue_s1ap_id, source_ue->mme_ue_s1ap_id);