diff --git a/components/bt/host/bluedroid/btc/profile/std/hf_client/bta_hf_client_co.c b/components/bt/host/bluedroid/btc/profile/std/hf_client/bta_hf_client_co.c
index b8b2ea40c7..99b9280304 100644
--- a/components/bt/host/bluedroid/btc/profile/std/hf_client/bta_hf_client_co.c
+++ b/components/bt/host/bluedroid/btc/profile/std/hf_client/bta_hf_client_co.c
@@ -73,8 +73,8 @@ static bta_hf_client_co_cb_t *bta_hf_client_co_cb_ptr;
 #define bta_hf_client_co_cb (*bta_hf_client_co_cb_ptr)
 #endif /* HFP_DYNAMIC_MEMORY == FALSE */
 
-static UINT8 hf_air_mode;
-static UINT8 hf_inout_pkt_size;
+static UINT8 hf_air_mode = BTM_SCO_AIR_MODE_UNKNOWN;
+static UINT8 hf_inout_pkt_size = 0;
 
 /*******************************************************************************
 **
@@ -223,6 +223,9 @@ void bta_hf_client_sco_co_open(UINT16 handle, UINT8 air_mode, UINT8 inout_pkt_si
 
 #if (HFP_DYNAMIC_MEMORY == TRUE)
 error_exit:;
+    hf_air_mode = BTM_SCO_AIR_MODE_UNKNOWN;
+    hf_inout_pkt_size = 0;
+
     if (bta_hf_client_co_cb_ptr) {
         osi_free(bta_hf_client_co_cb_ptr);
         bta_hf_client_co_cb_ptr = NULL;
@@ -271,6 +274,9 @@ void bta_hf_client_sco_co_close(void)
     } else {
         // Nothing to do
     }
+
+    hf_air_mode = BTM_SCO_AIR_MODE_UNKNOWN;
+    hf_inout_pkt_size = 0;
 }
 
 /*******************************************************************************
diff --git a/components/bt/host/bluedroid/stack/btu/btu_init.c b/components/bt/host/bluedroid/stack/btu/btu_init.c
index 52ce3a6e15..80678bef82 100644
--- a/components/bt/host/bluedroid/stack/btu/btu_init.c
+++ b/components/bt/host/bluedroid/stack/btu/btu_init.c
@@ -129,12 +129,12 @@ void btu_free_core(void)
 #if (defined(GATT_INCLUDED) && GATT_INCLUDED == true)
     gatt_free();
 #endif
-    btm_ble_free();
-#endif
-    btm_free();
 #if SMP_INCLUDED == TRUE
     SMP_Free();
 #endif
+    btm_ble_free();
+#endif
+    btm_free();
 }
 
 /*****************************************************************************
diff --git a/components/bt/host/bluedroid/stack/include/stack/btm_api.h b/components/bt/host/bluedroid/stack/include/stack/btm_api.h
index b51ecb0069..641dd93f52 100644
--- a/components/bt/host/bluedroid/stack/include/stack/btm_api.h
+++ b/components/bt/host/bluedroid/stack/include/stack/btm_api.h
@@ -983,6 +983,7 @@ typedef UINT16 tBTM_SCO_CODEC_TYPE;
 #define BTM_SCO_AIR_MODE_A_LAW          1
 #define BTM_SCO_AIR_MODE_CVSD           2
 #define BTM_SCO_AIR_MODE_TRANSPNT       3
+#define BTM_SCO_AIR_MODE_UNKNOWN        0xFF
 typedef UINT8 tBTM_SCO_AIR_MODE_TYPE;
 
 /*******************
diff --git a/examples/bluetooth/bluedroid/classic_bt/a2dp_sink/main/bt_app_core.c b/examples/bluetooth/bluedroid/classic_bt/a2dp_sink/main/bt_app_core.c
index a46c60050f..7dee9e7f40 100644
--- a/examples/bluetooth/bluedroid/classic_bt/a2dp_sink/main/bt_app_core.c
+++ b/examples/bluetooth/bluedroid/classic_bt/a2dp_sink/main/bt_app_core.c
@@ -26,7 +26,7 @@ static void bt_app_work_dispatched(bt_app_msg_t *msg);
 static xQueueHandle s_bt_app_task_queue = NULL;
 static xTaskHandle s_bt_app_task_handle = NULL;
 static xTaskHandle s_bt_i2s_task_handle = NULL;
-static RingbufHandle_t ringbuf_i2s = NULL;;
+static RingbufHandle_t s_ringbuf_i2s = NULL;;
 
 bool bt_app_work_dispatch(bt_app_cb_t p_cback, uint16_t event, void *p_params, int param_len, bt_app_copy_cb_t p_copy_cback)
 {
@@ -123,18 +123,18 @@ static void bt_i2s_task_handler(void *arg)
     size_t bytes_written = 0;
 
     for (;;) {
-        data = (uint8_t *)xRingbufferReceive(ringbuf_i2s, &item_size, (portTickType)portMAX_DELAY);
+        data = (uint8_t *)xRingbufferReceive(s_ringbuf_i2s, &item_size, (portTickType)portMAX_DELAY);
         if (item_size != 0){
             i2s_write(0, data, item_size, &bytes_written, portMAX_DELAY);
-            vRingbufferReturnItem(ringbuf_i2s,(void *)data);
+            vRingbufferReturnItem(s_ringbuf_i2s,(void *)data);
         }
     }
 }
 
 void bt_i2s_task_start_up(void)
 {
-    ringbuf_i2s = xRingbufferCreate(8 * 1024, RINGBUF_TYPE_BYTEBUF);
-    if(ringbuf_i2s == NULL){
+    s_ringbuf_i2s = xRingbufferCreate(8 * 1024, RINGBUF_TYPE_BYTEBUF);
+    if(s_ringbuf_i2s == NULL){
         return;
     }
 
@@ -149,13 +149,15 @@ void bt_i2s_task_shut_down(void)
         s_bt_i2s_task_handle = NULL;
     }
 
-    vRingbufferDelete(ringbuf_i2s);
-    ringbuf_i2s = NULL;
+    if (s_ringbuf_i2s) {
+        vRingbufferDelete(s_ringbuf_i2s);
+        s_ringbuf_i2s = NULL;
+    }
 }
 
 size_t write_ringbuf(const uint8_t *data, size_t size)
 {
-    BaseType_t done = xRingbufferSend(ringbuf_i2s, (void *)data, size, (portTickType)portMAX_DELAY);
+    BaseType_t done = xRingbufferSend(s_ringbuf_i2s, (void *)data, size, (portTickType)portMAX_DELAY);
     if(done){
         return size;
     } else {
diff --git a/examples/bluetooth/bluedroid/coex/a2dp_gatts_coex/main/bt_app_core.c b/examples/bluetooth/bluedroid/coex/a2dp_gatts_coex/main/bt_app_core.c
index a46c60050f..7dee9e7f40 100644
--- a/examples/bluetooth/bluedroid/coex/a2dp_gatts_coex/main/bt_app_core.c
+++ b/examples/bluetooth/bluedroid/coex/a2dp_gatts_coex/main/bt_app_core.c
@@ -26,7 +26,7 @@ static void bt_app_work_dispatched(bt_app_msg_t *msg);
 static xQueueHandle s_bt_app_task_queue = NULL;
 static xTaskHandle s_bt_app_task_handle = NULL;
 static xTaskHandle s_bt_i2s_task_handle = NULL;
-static RingbufHandle_t ringbuf_i2s = NULL;;
+static RingbufHandle_t s_ringbuf_i2s = NULL;;
 
 bool bt_app_work_dispatch(bt_app_cb_t p_cback, uint16_t event, void *p_params, int param_len, bt_app_copy_cb_t p_copy_cback)
 {
@@ -123,18 +123,18 @@ static void bt_i2s_task_handler(void *arg)
     size_t bytes_written = 0;
 
     for (;;) {
-        data = (uint8_t *)xRingbufferReceive(ringbuf_i2s, &item_size, (portTickType)portMAX_DELAY);
+        data = (uint8_t *)xRingbufferReceive(s_ringbuf_i2s, &item_size, (portTickType)portMAX_DELAY);
         if (item_size != 0){
             i2s_write(0, data, item_size, &bytes_written, portMAX_DELAY);
-            vRingbufferReturnItem(ringbuf_i2s,(void *)data);
+            vRingbufferReturnItem(s_ringbuf_i2s,(void *)data);
         }
     }
 }
 
 void bt_i2s_task_start_up(void)
 {
-    ringbuf_i2s = xRingbufferCreate(8 * 1024, RINGBUF_TYPE_BYTEBUF);
-    if(ringbuf_i2s == NULL){
+    s_ringbuf_i2s = xRingbufferCreate(8 * 1024, RINGBUF_TYPE_BYTEBUF);
+    if(s_ringbuf_i2s == NULL){
         return;
     }
 
@@ -149,13 +149,15 @@ void bt_i2s_task_shut_down(void)
         s_bt_i2s_task_handle = NULL;
     }
 
-    vRingbufferDelete(ringbuf_i2s);
-    ringbuf_i2s = NULL;
+    if (s_ringbuf_i2s) {
+        vRingbufferDelete(s_ringbuf_i2s);
+        s_ringbuf_i2s = NULL;
+    }
 }
 
 size_t write_ringbuf(const uint8_t *data, size_t size)
 {
-    BaseType_t done = xRingbufferSend(ringbuf_i2s, (void *)data, size, (portTickType)portMAX_DELAY);
+    BaseType_t done = xRingbufferSend(s_ringbuf_i2s, (void *)data, size, (portTickType)portMAX_DELAY);
     if(done){
         return size;
     } else {