diff --git a/ports/espressif/common-hal/_bleio/Adapter.c b/ports/espressif/common-hal/_bleio/Adapter.c
index f1c1ee986c..a5cf3da6ac 100644
--- a/ports/espressif/common-hal/_bleio/Adapter.c
+++ b/ports/espressif/common-hal/_bleio/Adapter.c
@@ -284,15 +284,21 @@ STATIC void _new_connection(uint16_t conn_handle) {
     esp_ble_tx_power_set(conn_handle, ESP_PWR_LVL_N0);
 
 
-    // Find an empty connection. One must always be available because the SD has the same
+    // Find an empty connection. One should always be available because the SD has the same
     // total connection limit.
-    bleio_connection_internal_t *connection;
+    bleio_connection_internal_t *connection = NULL;
     for (size_t i = 0; i < BLEIO_TOTAL_CONNECTION_COUNT; i++) {
         connection = &bleio_connections[i];
         if (connection->conn_handle == BLEIO_HANDLE_INVALID) {
             break;
         }
     }
+
+    // Shouldn't happen, but just return if no connection available.
+    if (!connection) {
+        return;
+    }
+
     connection->conn_handle = conn_handle;
     connection->connection_obj = mp_const_none;
     connection->pair_status = PAIR_NOT_PAIRED;
diff --git a/ports/espressif/common-hal/_bleio/Characteristic.c b/ports/espressif/common-hal/_bleio/Characteristic.c
index f639b75edf..0a787c017d 100644
--- a/ports/espressif/common-hal/_bleio/Characteristic.c
+++ b/ports/espressif/common-hal/_bleio/Characteristic.c
@@ -50,7 +50,25 @@ void common_hal_bleio_characteristic_construct(bleio_characteristic_obj_t *self,
     self->props = props;
     self->read_perm = read_perm;
     self->write_perm = write_perm;
-    common_hal_bleio_characteristic_set_value(self, initial_value_bufinfo);
+
+    if (initial_value_bufinfo != NULL) {
+        // Copy the initial value if it's on the heap. Otherwise it's internal and we may not be able
+        // to allocate.
+        self->current_value_len = initial_value_bufinfo->len;
+        if (gc_alloc_possible()) {
+            if (gc_nbytes(initial_value_bufinfo->buf) > 0) {
+                uint8_t *initial_value = m_malloc(self->current_value_len);
+                self->current_value_alloc = self->current_value_len;
+                memcpy(initial_value, initial_value_bufinfo->buf, self->current_value_len);
+                self->current_value = initial_value;
+            } else {
+                self->current_value_alloc = 0;
+                self->current_value = initial_value_bufinfo->buf;
+            }
+        } else {
+            self->current_value = initial_value_bufinfo->buf;
+        }
+    }
 
     if (gc_alloc_possible()) {
         self->descriptor_list = mp_obj_new_list(0, NULL);
diff --git a/ports/espressif/common-hal/_bleio/Connection.c b/ports/espressif/common-hal/_bleio/Connection.c
index 575d8d0894..2d10300bac 100644
--- a/ports/espressif/common-hal/_bleio/Connection.c
+++ b/ports/espressif/common-hal/_bleio/Connection.c
@@ -63,7 +63,7 @@ int bleio_connection_event_cb(struct ble_gap_event *event, void *connection_in)
             connection->pair_status = PAIR_NOT_PAIRED;
 
             #if CIRCUITPY_VERBOSE_BLE
-            mp_printf(&mp_plat_print, "disconnected %02x\n", event->disconnect.reason);
+            mp_printf(&mp_plat_print, "event->disconnect.reason: 0x%x\n", event->disconnect.reason);
             #endif
             if (connection->connection_obj != mp_const_none) {
                 bleio_connection_obj_t *obj = connection->connection_obj;
@@ -128,6 +128,7 @@ bool common_hal_bleio_connection_get_connected(bleio_connection_obj_t *self) {
 }
 
 void common_hal_bleio_connection_disconnect(bleio_connection_internal_t *self) {
+    // Second argument is an HCI reason, not an HS error code.
     ble_gap_terminate(self->conn_handle, BLE_ERR_REM_USER_CONN_TERM);
 }
 
@@ -162,9 +163,9 @@ STATIC int _discovered_service_cb(uint16_t conn_handle,
     void *arg) {
     bleio_connection_internal_t *self = (bleio_connection_internal_t *)arg;
 
-    if (error->status != BLE_ERR_SUCCESS) {
+    if (error->status != 0) {
         // Keep the first error in case it's due to memory.
-        if (_last_discovery_status == BLE_ERR_SUCCESS) {
+        if (_last_discovery_status == 0) {
             _last_discovery_status = error->status;
             xTaskNotifyGive(discovery_task);
         }
@@ -173,7 +174,7 @@ STATIC int _discovered_service_cb(uint16_t conn_handle,
 
     // If any of these memory allocations fail, we set _last_discovery_status
     // and let the process continue.
-    if (_last_discovery_status != BLE_ERR_SUCCESS) {
+    if (_last_discovery_status != 0) {
         return 0;
     }
     bleio_service_obj_t *service = mp_obj_malloc(bleio_service_obj_t, &bleio_service_type);
@@ -202,16 +203,17 @@ STATIC int _discovered_characteristic_cb(uint16_t conn_handle,
     void *arg) {
     bleio_service_obj_t *service = (bleio_service_obj_t *)arg;
 
-    if (error->status != BLE_ERR_SUCCESS) {
+    if (error->status != 0) {
         // Keep the first error in case it's due to memory.
-        if (_last_discovery_status == BLE_ERR_SUCCESS) {
+        if (_last_discovery_status == 0) {
             _last_discovery_status = error->status;
             xTaskNotifyGive(discovery_task);
         }
+        return 0;
     }
     // If any of these memory allocations fail, we set _last_discovery_status
     // and let the process continue.
-    if (_last_discovery_status != BLE_ERR_SUCCESS) {
+    if (_last_discovery_status != 0) {
         return 0;
     }
 
@@ -232,11 +234,14 @@ STATIC int _discovered_characteristic_cb(uint16_t conn_handle,
         ((chr->properties & BLE_GATT_CHR_PROP_WRITE_NO_RSP) != 0 ? CHAR_PROP_WRITE_NO_RESPONSE : 0);
 
     // Call common_hal_bleio_characteristic_construct() to initialize some fields and set up evt handler.
+    mp_buffer_info_t mp_const_empty_bytes_bufinfo;
+    mp_get_buffer_raise(mp_const_empty_bytes, &mp_const_empty_bytes_bufinfo, MP_BUFFER_READ);
+
     common_hal_bleio_characteristic_construct(
         characteristic, service, chr->val_handle, uuid,
         props, SECURITY_MODE_OPEN, SECURITY_MODE_OPEN,
         0, false,   // max_length, fixed_length: values don't matter for gattc
-        mp_const_empty_bytes,
+        &mp_const_empty_bytes_bufinfo,
         NULL);
     // Set def_handle directly since it is only used in discovery.
     characteristic->def_handle = chr->def_handle;
@@ -253,16 +258,17 @@ STATIC int _discovered_descriptor_cb(uint16_t conn_handle,
     void *arg) {
     bleio_characteristic_obj_t *characteristic = (bleio_characteristic_obj_t *)arg;
 
-    if (error->status != BLE_ERR_SUCCESS) {
+    if (error->status != 0) {
         // Keep the first error in case it's due to memory.
-        if (_last_discovery_status == BLE_ERR_SUCCESS) {
+        if (_last_discovery_status == 0) {
             _last_discovery_status = error->status;
         }
         xTaskNotifyGive(discovery_task);
+        return 0;
     }
     // If any of these memory allocations fail, we set _last_discovery_status
     // and let the process continue.
-    if (_last_discovery_status != BLE_ERR_SUCCESS) {
+    if (_last_discovery_status != 0) {
         return 0;
     }
 
@@ -306,7 +312,7 @@ STATIC void discover_remote_services(bleio_connection_internal_t *self, mp_obj_t
 
     discovery_task = xTaskGetCurrentTaskHandle();
     if (service_uuids_whitelist == mp_const_none) {
-        _last_discovery_status = BLE_ERR_SUCCESS;
+        _last_discovery_status = 0;
         CHECK_NIMBLE_ERROR(ble_gattc_disc_all_svcs(self->conn_handle, _discovered_service_cb, self));
 
         // Wait for sync.
@@ -324,7 +330,7 @@ STATIC void discover_remote_services(bleio_connection_internal_t *self, mp_obj_t
             }
             bleio_uuid_obj_t *uuid = MP_OBJ_TO_PTR(uuid_obj);
 
-            _last_discovery_status = BLE_ERR_SUCCESS;
+            _last_discovery_status = 0;
             // Make sure we start with a clean notification state
             ulTaskNotifyValueClear(discovery_task, 0xffffffff);
             CHECK_NIMBLE_ERROR(ble_gattc_disc_svc_by_uuid(self->conn_handle, &uuid->nimble_ble_uuid.u,
@@ -340,7 +346,7 @@ STATIC void discover_remote_services(bleio_connection_internal_t *self, mp_obj_t
     for (size_t i = 0; i < self->remote_service_list->len; i++) {
         bleio_service_obj_t *service = MP_OBJ_TO_PTR(self->remote_service_list->items[i]);
 
-        _last_discovery_status = BLE_ERR_SUCCESS;
+        _last_discovery_status = 0;
         CHECK_NIMBLE_ERROR(ble_gattc_disc_all_chrs(self->conn_handle,
             service->start_handle,
             service->end_handle,
@@ -375,7 +381,7 @@ STATIC void discover_remote_services(bleio_connection_internal_t *self, mp_obj_t
                 continue;
             }
 
-            _last_discovery_status = BLE_ERR_SUCCESS;
+            _last_discovery_status = 0;
             CHECK_NIMBLE_ERROR(ble_gattc_disc_all_dscs(self->conn_handle, characteristic->handle,
                 end_handle,
                 _discovered_descriptor_cb, characteristic));
diff --git a/ports/espressif/common-hal/_bleio/__init__.c b/ports/espressif/common-hal/_bleio/__init__.c
index f6ac17012d..338f576f69 100644
--- a/ports/espressif/common-hal/_bleio/__init__.c
+++ b/ports/espressif/common-hal/_bleio/__init__.c
@@ -112,7 +112,8 @@ void check_nimble_error(int rc, const char *file, size_t line) {
 }
 
 void check_ble_error(int error_code, const char *file, size_t line) {
-    if (error_code == BLE_ERR_SUCCESS) {
+    // 0 means success. For BLE_HS_* codes, there is no defined "SUCCESS" value.
+    if (error_code == 0) {
         return;
     }
     switch (error_code) {
diff --git a/ports/espressif/mpconfigport.h b/ports/espressif/mpconfigport.h
index f94fd1ce0c..1a97d1b6de 100644
--- a/ports/espressif/mpconfigport.h
+++ b/ports/espressif/mpconfigport.h
@@ -28,6 +28,9 @@
 #ifndef MICROPY_INCLUDED_ESPRESSIF_MPCONFIGPORT_H
 #define MICROPY_INCLUDED_ESPRESSIF_MPCONFIGPORT_H
 
+// Enable for debugging.
+// #define CIRCUITPY_VERBOSE_BLE               (1)
+
 #define MICROPY_NLR_THUMB                   (0)
 
 #define MICROPY_USE_INTERNAL_PRINTF         (0)
diff --git a/py/circuitpy_mpconfig.h b/py/circuitpy_mpconfig.h
index b962f3892d..30f3101a38 100644
--- a/py/circuitpy_mpconfig.h
+++ b/py/circuitpy_mpconfig.h
@@ -470,7 +470,9 @@ void background_callback_run_all(void);
 #error "boot counter requires CIRCUITPY_NVM enabled"
 #endif
 
+#ifndef CIRCUITPY_VERBOSE_BLE
 #define CIRCUITPY_VERBOSE_BLE 0
+#endif
 
 // Display the Blinka logo in the REPL on displayio displays.
 #ifndef CIRCUITPY_REPL_LOGO
diff --git a/shared-bindings/_bleio/Adapter.c b/shared-bindings/_bleio/Adapter.c
index 43d146434b..005f30f8b3 100644
--- a/shared-bindings/_bleio/Adapter.c
+++ b/shared-bindings/_bleio/Adapter.c
@@ -353,7 +353,8 @@ STATIC mp_obj_t bleio_adapter_start_scan(size_t n_args, const mp_obj_t *pos_args
     prefix_bufinfo.len = 0;
     if (args[ARG_prefixes].u_obj != MP_OBJ_NULL) {
         mp_get_buffer_raise(args[ARG_prefixes].u_obj, &prefix_bufinfo, MP_BUFFER_READ);
-        if (gc_nbytes(prefix_bufinfo.buf) == 0) {
+        // An empty buffer may not be on the heap, but that doesn't matter.
+        if (prefix_bufinfo.len > 0 && gc_nbytes(prefix_bufinfo.buf) == 0) {
             mp_raise_ValueError(MP_ERROR_TEXT("Prefix buffer must be on the heap"));
         }
     }