diff --git a/modules/openthread/platform/ble.c b/modules/openthread/platform/ble.c
index 55330e1ffe7..7ceadfbd86e 100644
--- a/modules/openthread/platform/ble.c
+++ b/modules/openthread/platform/ble.c
@@ -322,7 +322,8 @@ static void connected(struct bt_conn *conn, uint8_t err)
 	ot_plat_ble_connection = bt_conn_ref(conn);
 
 	if (err) {
-		LOG_WRN("Connection failed (err %u)", err);
+		LOG_WRN("Connection failed err %u %s",
+			err, bt_hci_err_to_str(err));
 		return;
 	} else if (bt_conn_get_info(conn, &info)) {
 		LOG_WRN("Could not parse connection info");
@@ -342,7 +343,7 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 {
 	otError error = OT_ERROR_NONE;
 
-	LOG_INF("Disconnected (reason %" PRIu8 ")", reason);
+	LOG_INF("Disconnected, reason 0x%02x %s", reason, bt_hci_err_to_str(reason));
 
 	if (ot_plat_ble_connection) {
 		bt_conn_unref(ot_plat_ble_connection);
diff --git a/samples/bluetooth/bap_broadcast_assistant/src/main.c b/samples/bluetooth/bap_broadcast_assistant/src/main.c
index 081f5bc842a..eb58bb6a0e5 100644
--- a/samples/bluetooth/bap_broadcast_assistant/src/main.c
+++ b/samples/bluetooth/bap_broadcast_assistant/src/main.c
@@ -439,7 +439,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 	(void)bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
 	if (err != 0) {
-		printk("Failed to connect to %s (%u)\n", addr, err);
+		printk("Failed to connect to %s %u %s\n", addr, err, bt_hci_err_to_str(err));
 
 		bt_conn_unref(broadcast_sink_conn);
 		broadcast_sink_conn = NULL;
@@ -466,7 +466,7 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 
 	(void)bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
-	printk("Disconnected: %s (reason 0x%02x)\n", addr, reason);
+	printk("Disconnected: %s, reason 0x%02x %s\n", addr, reason, bt_hci_err_to_str(reason));
 
 	bt_conn_unref(broadcast_sink_conn);
 	broadcast_sink_conn = NULL;
@@ -481,7 +481,7 @@ static void security_changed_cb(struct bt_conn *conn, bt_security_t level,
 		printk("Security level changed: %u\n", level);
 		k_sem_give(&sem_security_updated);
 	} else {
-		printk("Failed to set security level: %u\n", err);
+		printk("Failed to set security level: %s(%u)\n", bt_security_err_to_str(err), err);
 	}
 }
 
diff --git a/samples/bluetooth/bap_broadcast_sink/src/main.c b/samples/bluetooth/bap_broadcast_sink/src/main.c
index d443170e174..c4432f9389c 100644
--- a/samples/bluetooth/bap_broadcast_sink/src/main.c
+++ b/samples/bluetooth/bap_broadcast_sink/src/main.c
@@ -1063,7 +1063,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
 	if (err != 0U) {
-		printk("Failed to connect to %s (%u)\n", addr, err);
+		printk("Failed to connect to %s %u %s\n", addr, err, bt_hci_err_to_str(err));
 
 		broadcast_assistant_conn = NULL;
 		return;
@@ -1085,7 +1085,7 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
-	printk("Disconnected: %s (reason 0x%02x)\n", addr, reason);
+	printk("Disconnected: %s, reason 0x%02x %s\n", addr, reason, bt_hci_err_to_str(reason));
 
 	bt_conn_unref(broadcast_assistant_conn);
 	broadcast_assistant_conn = NULL;
diff --git a/samples/bluetooth/bap_unicast_client/src/main.c b/samples/bluetooth/bap_unicast_client/src/main.c
index cc8e5d7d6d8..1fccebe6738 100644
--- a/samples/bluetooth/bap_unicast_client/src/main.c
+++ b/samples/bluetooth/bap_unicast_client/src/main.c
@@ -395,7 +395,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 	(void)bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
 	if (err != 0) {
-		printk("Failed to connect to %s (%u)\n", addr, err);
+		printk("Failed to connect to %s %u %s\n", addr, err, bt_hci_err_to_str(err));
 
 		bt_conn_unref(default_conn);
 		default_conn = NULL;
@@ -422,7 +422,7 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 
 	(void)bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
-	printk("Disconnected: %s (reason 0x%02x)\n", addr, reason);
+	printk("Disconnected: %s, reason 0x%02x %s\n", addr, reason, bt_hci_err_to_str(reason));
 
 	bt_conn_unref(default_conn);
 	default_conn = NULL;
@@ -436,7 +436,7 @@ static void security_changed_cb(struct bt_conn *conn, bt_security_t level,
 	if (err == 0) {
 		k_sem_give(&sem_security_updated);
 	} else {
-		printk("Failed to set security level: %u", err);
+		printk("Failed to set security level: %s(%u)", bt_security_err_to_str(err), err);
 	}
 }
 
diff --git a/samples/bluetooth/bap_unicast_server/src/main.c b/samples/bluetooth/bap_unicast_server/src/main.c
index 7763484d1a5..90bff48719f 100644
--- a/samples/bluetooth/bap_unicast_server/src/main.c
+++ b/samples/bluetooth/bap_unicast_server/src/main.c
@@ -583,7 +583,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
 	if (err != 0) {
-		printk("Failed to connect to %s (%u)\n", addr, err);
+		printk("Failed to connect to %s %u %s\n", addr, err, bt_hci_err_to_str(err));
 
 		default_conn = NULL;
 		return;
@@ -603,7 +603,7 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
-	printk("Disconnected: %s (reason 0x%02x)\n", addr, reason);
+	printk("Disconnected: %s, reason 0x%02x %s\n", addr, reason, bt_hci_err_to_str(reason));
 
 	bt_conn_unref(default_conn);
 	default_conn = NULL;
diff --git a/samples/bluetooth/cap_acceptor/src/main.c b/samples/bluetooth/cap_acceptor/src/main.c
index fe53bcb7eaa..6ca5f59282e 100644
--- a/samples/bluetooth/cap_acceptor/src/main.c
+++ b/samples/bluetooth/cap_acceptor/src/main.c
@@ -82,7 +82,7 @@ static void disconnected_cb(struct bt_conn *conn, uint8_t reason)
 	}
 
 	(void)bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
-	LOG_INF("Disconnected: %s (reason 0x%02x)", addr, reason);
+	LOG_INF("Disconnected: %s, reason 0x%02x %s", addr, reason, bt_hci_err_to_str(reason));
 
 	bt_conn_unref(peer.conn);
 	peer.conn = NULL;
diff --git a/samples/bluetooth/cap_initiator/src/cap_initiator_unicast.c b/samples/bluetooth/cap_initiator/src/cap_initiator_unicast.c
index 030fe3835c3..7da8617912a 100644
--- a/samples/bluetooth/cap_initiator/src/cap_initiator_unicast.c
+++ b/samples/bluetooth/cap_initiator/src/cap_initiator_unicast.c
@@ -522,7 +522,7 @@ static void disconnected_cb(struct bt_conn *conn, uint8_t reason)
 
 	(void)bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
-	LOG_INF("Disconnected: %s (reason 0x%02x)", addr, reason);
+	LOG_INF("Disconnected: %s, reason 0x%02x %s", addr, reason, bt_hci_err_to_str(reason));
 
 	bt_conn_unref(peer.conn);
 	peer.conn = NULL;
@@ -537,7 +537,8 @@ static void security_changed_cb(struct bt_conn *conn, bt_security_t level,
 		LOG_INF("Security changed: %u", level);
 		k_sem_give(&sem_security_changed);
 	} else {
-		LOG_ERR("Failed to set security level: %d", sec_err);
+		LOG_ERR("Failed to set security level: %s(%d)",
+			bt_security_err_to_str(sec_err), sec_err);
 
 		if (sec_err == BT_SECURITY_ERR_PIN_OR_KEY_MISSING) {
 			int err;
diff --git a/samples/bluetooth/central/src/main.c b/samples/bluetooth/central/src/main.c
index e6305ea70b6..85ce435e923 100644
--- a/samples/bluetooth/central/src/main.c
+++ b/samples/bluetooth/central/src/main.c
@@ -80,7 +80,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
 	if (err) {
-		printk("Failed to connect to %s (%u)\n", addr, err);
+		printk("Failed to connect to %s %u %s\n", addr, err, bt_hci_err_to_str(err));
 
 		bt_conn_unref(default_conn);
 		default_conn = NULL;
@@ -108,7 +108,7 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
-	printk("Disconnected: %s (reason 0x%02x)\n", addr, reason);
+	printk("Disconnected: %s, reason 0x%02x %s\n", addr, reason, bt_hci_err_to_str(reason));
 
 	bt_conn_unref(default_conn);
 	default_conn = NULL;
diff --git a/samples/bluetooth/central_gatt_write/src/central_gatt_write.c b/samples/bluetooth/central_gatt_write/src/central_gatt_write.c
index fada73d9d94..2f3bd6b47c9 100644
--- a/samples/bluetooth/central_gatt_write/src/central_gatt_write.c
+++ b/samples/bluetooth/central_gatt_write/src/central_gatt_write.c
@@ -10,6 +10,7 @@
 #include <zephyr/bluetooth/bluetooth.h>
 #include <zephyr/bluetooth/conn.h>
 #include <zephyr/bluetooth/gatt.h>
+#include <zephyr/bluetooth/hci.h>
 
 extern int mtu_exchange(struct bt_conn *conn);
 extern int write_cmd(struct bt_conn *conn);
diff --git a/samples/bluetooth/central_gatt_write/src/gatt_write_common.c b/samples/bluetooth/central_gatt_write/src/gatt_write_common.c
index 7deecd11219..7bd597e95dc 100644
--- a/samples/bluetooth/central_gatt_write/src/gatt_write_common.c
+++ b/samples/bluetooth/central_gatt_write/src/gatt_write_common.c
@@ -10,6 +10,7 @@
 #include <zephyr/bluetooth/bluetooth.h>
 #include <zephyr/bluetooth/conn.h>
 #include <zephyr/bluetooth/gatt.h>
+#include <zephyr/bluetooth/hci.h>
 
 static struct bt_gatt_exchange_params mtu_exchange_params;
 static uint32_t write_count;
@@ -134,8 +135,8 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 		return;
 	}
 
-	printk("%s: %s role %u (reason %u)\n", __func__, addr, conn_info.role,
-	       reason);
+	printk("%s: %s role %u, reason %u %s\n", __func__, addr, conn_info.role,
+	       reason, bt_hci_err_to_str(reason));
 
 	conn_connected = NULL;
 
@@ -166,7 +167,7 @@ static void le_param_updated(struct bt_conn *conn, uint16_t interval,
 static void security_changed(struct bt_conn *conn, bt_security_t level,
 			     enum bt_security_err err)
 {
-	printk("%s: to level %u (err %u)\n", __func__, level, err);
+	printk("%s: to level %u, err %s(%u)\n", __func__, level, bt_security_err_to_str(err), err);
 }
 #endif
 
diff --git a/samples/bluetooth/central_hr/src/main.c b/samples/bluetooth/central_hr/src/main.c
index 95f45f7c140..622bd4a7a3a 100644
--- a/samples/bluetooth/central_hr/src/main.c
+++ b/samples/bluetooth/central_hr/src/main.c
@@ -252,7 +252,7 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
-	printk("Disconnected: %s (reason 0x%02x)\n", addr, reason);
+	printk("Disconnected: %s, reason 0x%02x %s\n", addr, reason, bt_hci_err_to_str(reason));
 
 	if (default_conn != conn) {
 		return;
diff --git a/samples/bluetooth/central_ht/src/main.c b/samples/bluetooth/central_ht/src/main.c
index cc9bdae61c1..18cfc9f69d5 100644
--- a/samples/bluetooth/central_ht/src/main.c
+++ b/samples/bluetooth/central_ht/src/main.c
@@ -243,7 +243,7 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
-	printk("Disconnected: %s (reason 0x%02x)\n", addr, reason);
+	printk("Disconnected: %s, reason 0x%02x %s\n", addr, reason, bt_hci_err_to_str(reason));
 
 	if (default_conn != conn) {
 		return;
diff --git a/samples/bluetooth/central_iso/src/main.c b/samples/bluetooth/central_iso/src/main.c
index 444887911b8..65d1abb4914 100644
--- a/samples/bluetooth/central_iso/src/main.c
+++ b/samples/bluetooth/central_iso/src/main.c
@@ -179,7 +179,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
 	if (err) {
-		printk("Failed to connect to %s (%u)\n", addr, err);
+		printk("Failed to connect to %s %u %s\n", addr, err, bt_hci_err_to_str(err));
 
 		bt_conn_unref(default_conn);
 		default_conn = NULL;
@@ -215,7 +215,7 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
-	printk("Disconnected: %s (reason 0x%02x)\n", addr, reason);
+	printk("Disconnected: %s, reason 0x%02x %s\n", addr, reason, bt_hci_err_to_str(reason));
 
 	bt_conn_unref(default_conn);
 	default_conn = NULL;
diff --git a/samples/bluetooth/central_multilink/src/central_multilink.c b/samples/bluetooth/central_multilink/src/central_multilink.c
index eb5989587fe..26a2e674ce7 100644
--- a/samples/bluetooth/central_multilink/src/central_multilink.c
+++ b/samples/bluetooth/central_multilink/src/central_multilink.c
@@ -182,7 +182,7 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
-	printk("Disconnected: %s (reason 0x%02x)\n", addr, reason);
+	printk("Disconnected: %s, reason 0x%02x %s\n", addr, reason, bt_hci_err_to_str(reason));
 
 	bt_conn_unref(conn);
 
@@ -228,8 +228,8 @@ static void security_changed(struct bt_conn *conn, bt_security_t level,
 	if (!err) {
 		printk("Security changed: %s level %u\n", addr, level);
 	} else {
-		printk("Security failed: %s level %u err %d\n", addr, level,
-		       err);
+		printk("Security failed: %s level %u err %d %s\n", addr, level,
+		       err, bt_security_err_to_str(err));
 	}
 }
 #endif
diff --git a/samples/bluetooth/central_otc/src/main.c b/samples/bluetooth/central_otc/src/main.c
index 7c2c659f510..23a2968e14a 100644
--- a/samples/bluetooth/central_otc/src/main.c
+++ b/samples/bluetooth/central_otc/src/main.c
@@ -502,7 +502,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 	first_selected = false;
 	if (err != 0) {
-		printk("Failed to connect to %s (%u)\n", addr, err);
+		printk("Failed to connect to %s %u %s\n", addr, err, bt_hci_err_to_str(err));
 
 		bt_conn_unref(default_conn);
 		default_conn = NULL;
@@ -542,7 +542,7 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
-	printk("Disconnected: %s (reason 0x%02x)\n", addr, reason);
+	printk("Disconnected: %s, reason 0x%02x %s\n", addr, reason, bt_hci_err_to_str(reason));
 
 	bt_conn_unref(default_conn);
 	default_conn = NULL;
diff --git a/samples/bluetooth/central_past/src/main.c b/samples/bluetooth/central_past/src/main.c
index fd40ed5e296..458fe763eff 100644
--- a/samples/bluetooth/central_past/src/main.c
+++ b/samples/bluetooth/central_past/src/main.c
@@ -9,6 +9,7 @@
 #include <zephyr/drivers/gpio.h>
 #include <zephyr/bluetooth/bluetooth.h>
 #include <zephyr/bluetooth/conn.h>
+#include <zephyr/bluetooth/hci.h>
 
 #define NAME_LEN            30
 
@@ -128,7 +129,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
 	if (err != 0) {
-		printk("Failed to connect to %s (%u)\n", addr, err);
+		printk("Failed to connect to %s %u %s\n", addr, err, bt_hci_err_to_str(err));
 
 		bt_conn_unref(default_conn);
 		default_conn = NULL;
@@ -163,7 +164,7 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
-	printk("Disconnected: %s (reason 0x%02x)\n", addr, reason);
+	printk("Disconnected: %s, reason 0x%02x %s\n", addr, reason, bt_hci_err_to_str(reason));
 
 	bt_conn_unref(default_conn);
 	default_conn = NULL;
diff --git a/samples/bluetooth/direct_adv/src/main.c b/samples/bluetooth/direct_adv/src/main.c
index 97734ae83f0..a381cf0c1e2 100644
--- a/samples/bluetooth/direct_adv/src/main.c
+++ b/samples/bluetooth/direct_adv/src/main.c
@@ -82,7 +82,7 @@ static const struct bt_data ad[] = {
 static void connected(struct bt_conn *conn, uint8_t err)
 {
 	if (err) {
-		printk("Connection failed (err 0x%02x)\n", err);
+		printk("Connection failed err 0x%02x %s\n", err, bt_hci_err_to_str(err));
 	} else {
 		printk("Connected\n");
 	}
@@ -90,7 +90,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 
 static void disconnected(struct bt_conn *conn, uint8_t reason)
 {
-	printk("Disconnected (reason 0x%02x)\n", reason);
+	printk("Disconnected, reason 0x%02x %s\n", reason, bt_hci_err_to_str(reason));
 }
 
 BT_CONN_CB_DEFINE(conn_callbacks) = {
diff --git a/samples/bluetooth/direction_finding_central/src/main.c b/samples/bluetooth/direction_finding_central/src/main.c
index 04a49ef20f3..45e31add8fd 100644
--- a/samples/bluetooth/direction_finding_central/src/main.c
+++ b/samples/bluetooth/direction_finding_central/src/main.c
@@ -232,7 +232,7 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
-	printk("Disconnected: %s (reason 0x%02x)\n", addr, reason);
+	printk("Disconnected: %s, reason 0x%02x %s\n", addr, reason, bt_hci_err_to_str(reason));
 
 	if (default_conn != conn) {
 		return;
diff --git a/samples/bluetooth/direction_finding_peripheral/src/main.c b/samples/bluetooth/direction_finding_peripheral/src/main.c
index 214449c3580..da4cd72888a 100644
--- a/samples/bluetooth/direction_finding_peripheral/src/main.c
+++ b/samples/bluetooth/direction_finding_peripheral/src/main.c
@@ -76,7 +76,7 @@ static void enable_cte_response(struct bt_conn *conn)
 static void connected(struct bt_conn *conn, uint8_t err)
 {
 	if (err) {
-		printk("Connection failed (err 0x%02x)\n", err);
+		printk("Connection failed err 0x%02x %s\n", err, bt_hci_err_to_str(err));
 	} else {
 		printk("Connected\n");
 	}
@@ -86,7 +86,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 
 static void disconnected(struct bt_conn *conn, uint8_t reason)
 {
-	printk("Disconnected (reason 0x%02x)\n", reason);
+	printk("Disconnected, reason 0x%02x %s\n", reason, bt_hci_err_to_str(reason));
 }
 
 BT_CONN_CB_DEFINE(conn_callbacks) = {
diff --git a/samples/bluetooth/eddystone/src/main.c b/samples/bluetooth/eddystone/src/main.c
index 33a01396c91..8bc3213f880 100644
--- a/samples/bluetooth/eddystone/src/main.c
+++ b/samples/bluetooth/eddystone/src/main.c
@@ -661,7 +661,7 @@ static void idle_timeout(struct k_work *work)
 static void connected(struct bt_conn *conn, uint8_t err)
 {
 	if (err) {
-		printk("Connection failed (err 0x%02x)\n", err);
+		printk("Connection failed err 0x%02x %s\n", err, bt_hci_err_to_str(err));
 	} else {
 		printk("Connected\n");
 		k_work_cancel_delayable(&idle_work);
@@ -672,7 +672,7 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 {
 	struct eds_slot *slot = &eds_slots[eds_active_slot];
 
-	printk("Disconnected (reason 0x%02x)\n", reason);
+	printk("Disconnected, reason 0x%02x %s\n", reason, bt_hci_err_to_str(reason));
 
 	if (!slot->connectable) {
 		k_work_reschedule(&idle_work, K_NO_WAIT);
diff --git a/samples/bluetooth/encrypted_advertising/central/src/central_ead.c b/samples/bluetooth/encrypted_advertising/central/src/central_ead.c
index ddfb98cad8a..9c6361bb6d0 100644
--- a/samples/bluetooth/encrypted_advertising/central/src/central_ead.c
+++ b/samples/bluetooth/encrypted_advertising/central/src/central_ead.c
@@ -19,6 +19,7 @@
 #include <zephyr/bluetooth/addr.h>
 #include <zephyr/bluetooth/conn.h>
 #include <zephyr/bluetooth/uuid.h>
+#include <zephyr/bluetooth/hci.h>
 #include <zephyr/bluetooth/bluetooth.h>
 
 #include "common/bt_str.h"
@@ -329,7 +330,7 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
-	LOG_DBG("Disconnected: %s (reason 0x%02x)", addr, reason);
+	LOG_DBG("Disconnected: %s, reason 0x%02x %s", addr, reason, bt_hci_err_to_str(reason));
 
 	if (default_conn != conn) {
 		return;
@@ -348,7 +349,8 @@ static void security_changed(struct bt_conn *conn, bt_security_t level, enum bt_
 	if (!err) {
 		LOG_DBG("Security changed: %s level %u", addr, level);
 	} else {
-		LOG_DBG("Security failed: %s level %u err %d", addr, level, err);
+		LOG_DBG("Security failed: %s level %u err %d %s", addr, level,
+			err, bt_security_err_to_str(err));
 	}
 }
 
diff --git a/samples/bluetooth/encrypted_advertising/peripheral/src/peripheral_ead.c b/samples/bluetooth/encrypted_advertising/peripheral/src/peripheral_ead.c
index e994700f4cf..d2476d2ce82 100644
--- a/samples/bluetooth/encrypted_advertising/peripheral/src/peripheral_ead.c
+++ b/samples/bluetooth/encrypted_advertising/peripheral/src/peripheral_ead.c
@@ -17,6 +17,7 @@
 #include <zephyr/bluetooth/conn.h>
 #include <zephyr/bluetooth/gatt.h>
 #include <zephyr/bluetooth/uuid.h>
+#include <zephyr/bluetooth/hci.h>
 #include <zephyr/bluetooth/bluetooth.h>
 
 #include <zephyr/logging/log.h>
@@ -198,7 +199,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
 	if (err) {
-		LOG_ERR("Failed to connect to %s (%u)", addr, err);
+		LOG_ERR("Failed to connect to %s %u %s", addr, err, bt_hci_err_to_str(err));
 		return;
 	}
 
@@ -213,7 +214,7 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
-	LOG_DBG("Disconnected from %s (reason 0x%02x)", addr, reason);
+	LOG_DBG("Disconnected from %s, reason 0x%02x %s", addr, reason, bt_hci_err_to_str(reason));
 
 	k_poll_signal_raise(&disconn_signal, 0);
 }
@@ -227,7 +228,8 @@ static void security_changed(struct bt_conn *conn, bt_security_t level, enum bt_
 	if (!err) {
 		LOG_DBG("Security changed: %s level %u", addr, level);
 	} else {
-		LOG_DBG("Security failed: %s level %u err %d", addr, level, err);
+		LOG_DBG("Security failed: %s level %u err %s(%d)", addr, level,
+			bt_security_err_to_str(err), err);
 	}
 }
 
diff --git a/samples/bluetooth/extended_adv/advertiser/src/main.c b/samples/bluetooth/extended_adv/advertiser/src/main.c
index eccbf7b0967..66cdb6cee8f 100644
--- a/samples/bluetooth/extended_adv/advertiser/src/main.c
+++ b/samples/bluetooth/extended_adv/advertiser/src/main.c
@@ -7,6 +7,7 @@
 #include <zephyr/bluetooth/bluetooth.h>
 #include <zephyr/bluetooth/conn.h>
 #include <zephyr/bluetooth/gap.h>
+#include <zephyr/bluetooth/hci.h>
 
 static struct bt_conn *default_conn;
 
@@ -51,7 +52,7 @@ static void connected_cb(struct bt_conn *conn, uint8_t err)
 
 static void disconnected_cb(struct bt_conn *conn, uint8_t reason)
 {
-	printk("Disconnected (reason 0x%02X)\n", reason);
+	printk("Disconnected, reason 0x%02X %s\n", reason, bt_hci_err_to_str(reason));
 
 	__ASSERT(conn == default_conn, "Unexpected disconnected callback");
 
diff --git a/samples/bluetooth/extended_adv/scanner/src/main.c b/samples/bluetooth/extended_adv/scanner/src/main.c
index a4773830fc3..137a083c63c 100644
--- a/samples/bluetooth/extended_adv/scanner/src/main.c
+++ b/samples/bluetooth/extended_adv/scanner/src/main.c
@@ -7,6 +7,7 @@
 #include <zephyr/kernel.h>
 #include <zephyr/bluetooth/bluetooth.h>
 #include <zephyr/bluetooth/conn.h>
+#include <zephyr/bluetooth/hci.h>
 
 #define NAME_LEN 30
 
@@ -60,7 +61,7 @@ static void disconnected_cb(struct bt_conn *conn, uint8_t reason)
 	bt_conn_unref(default_conn);
 	default_conn = NULL;
 
-	printk("Disconnected (reason 0x%02X)\n", reason);
+	printk("Disconnected, reason 0x%02X %s\n", reason, bt_hci_err_to_str(reason));
 }
 
 static void recycled_cb(void)
diff --git a/samples/bluetooth/handsfree_ag/src/main.c b/samples/bluetooth/handsfree_ag/src/main.c
index 03c76eb0805..5a0e8fe6cd0 100644
--- a/samples/bluetooth/handsfree_ag/src/main.c
+++ b/samples/bluetooth/handsfree_ag/src/main.c
@@ -17,6 +17,7 @@
 #include <zephyr/bluetooth/bluetooth.h>
 #include <zephyr/bluetooth/conn.h>
 #include <zephyr/bluetooth/l2cap.h>
+#include <zephyr/bluetooth/hci.h>
 #include <zephyr/bluetooth/classic/rfcomm.h>
 #include <zephyr/bluetooth/classic/sdp.h>
 #include <zephyr/bluetooth/classic/hfp_ag.h>
@@ -148,7 +149,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 		if (default_conn != NULL) {
 			default_conn = NULL;
 		}
-		printk("Connection failed (err 0x%02x)\n", err);
+		printk("Connection failed, err 0x%02x %s\n", err, bt_hci_err_to_str(err));
 	} else {
 		if (default_conn == conn) {
 			struct bt_conn_info info;
@@ -175,7 +176,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 
 static void disconnected(struct bt_conn *conn, uint8_t reason)
 {
-	printk("Disconnected (reason 0x%02x)\n", reason);
+	printk("Disconnected, reason 0x%02x %s\n", reason, bt_hci_err_to_str(reason));
 
 	if (default_conn != conn) {
 		return;
@@ -197,7 +198,8 @@ static void security_changed(struct bt_conn *conn, bt_security_t level, enum bt_
 
 	bt_addr_to_str(info.br.dst, addr, sizeof(addr));
 
-	printk("Security changed: %s level %u (err %d)\n", addr, level, err);
+	printk("Security changed: %s level %u, err %s(%d)\n", addr, level,
+	       bt_security_err_to_str(err), err);
 }
 
 static struct bt_conn_cb conn_callbacks = {
diff --git a/samples/bluetooth/hap_ha/src/bap_unicast_sr.c b/samples/bluetooth/hap_ha/src/bap_unicast_sr.c
index e2b4b3022de..6244bb76bf1 100644
--- a/samples/bluetooth/hap_ha/src/bap_unicast_sr.c
+++ b/samples/bluetooth/hap_ha/src/bap_unicast_sr.c
@@ -13,6 +13,7 @@
 
 #include <zephyr/bluetooth/bluetooth.h>
 #include <zephyr/bluetooth/conn.h>
+#include <zephyr/bluetooth/hci.h>
 #include <zephyr/bluetooth/audio/audio.h>
 #include <zephyr/bluetooth/audio/bap.h>
 #include <zephyr/bluetooth/audio/pacs.h>
@@ -344,7 +345,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
 	if (err != 0) {
-		printk("Failed to connect to %s (%u)\n", addr, err);
+		printk("Failed to connect to %s %u %s\n", addr, err, bt_hci_err_to_str(err));
 
 		default_conn = NULL;
 		return;
@@ -365,7 +366,7 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
-	printk("Disconnected: %s (reason 0x%02x)\n", addr, reason);
+	printk("Disconnected: %s, reason 0x%02x %s\n", addr, reason, bt_hci_err_to_str(reason));
 
 	bt_conn_unref(default_conn);
 	default_conn = NULL;
diff --git a/samples/bluetooth/hap_ha/src/ccp_call_ctrl.c b/samples/bluetooth/hap_ha/src/ccp_call_ctrl.c
index 8f73e47d317..8b7eda13c58 100644
--- a/samples/bluetooth/hap_ha/src/ccp_call_ctrl.c
+++ b/samples/bluetooth/hap_ha/src/ccp_call_ctrl.c
@@ -12,6 +12,7 @@
 #include <zephyr/sys/util.h>
 
 #include <zephyr/bluetooth/conn.h>
+#include <zephyr/bluetooth/hci.h>
 #include <zephyr/bluetooth/audio/tbs.h>
 
 enum {
@@ -61,7 +62,7 @@ static int process_profile_connection(struct bt_conn *conn)
 static void connected(struct bt_conn *conn, uint8_t err)
 {
 	if (err) {
-		printk("Connection failed (err %d)\n", err);
+		printk("Connection failed, err %d %s\n", err, bt_hci_err_to_str(err));
 		return;
 	}
 
diff --git a/samples/bluetooth/hci_pwr_ctrl/src/main.c b/samples/bluetooth/hci_pwr_ctrl/src/main.c
index 4e1da7b6aee..42ef4d214ca 100644
--- a/samples/bluetooth/hci_pwr_ctrl/src/main.c
+++ b/samples/bluetooth/hci_pwr_ctrl/src/main.c
@@ -146,7 +146,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 	int ret;
 
 	if (err) {
-		printk("Connection failed (err 0x%02x)\n", err);
+		printk("Connection failed, err 0x%02x %s\n", err, bt_hci_err_to_str(err));
 	} else {
 		default_conn = bt_conn_ref(conn);
 		ret = bt_hci_get_conn_handle(default_conn,
@@ -177,7 +177,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 
 static void disconnected(struct bt_conn *conn, uint8_t reason)
 {
-	printk("Disconnected (reason 0x%02x)\n", reason);
+	printk("Disconnected, reason 0x%02x %s\n", reason, bt_hci_err_to_str(reason));
 
 	if (default_conn) {
 		bt_conn_unref(default_conn);
diff --git a/samples/bluetooth/iso_connected_benchmark/src/main.c b/samples/bluetooth/iso_connected_benchmark/src/main.c
index 9873a4c71f4..ff694b4a1cf 100644
--- a/samples/bluetooth/iso_connected_benchmark/src/main.c
+++ b/samples/bluetooth/iso_connected_benchmark/src/main.c
@@ -14,6 +14,7 @@
 #include <zephyr/console/console.h>
 #include <zephyr/bluetooth/bluetooth.h>
 #include <zephyr/bluetooth/iso.h>
+#include <zephyr/bluetooth/hci.h>
 #include <zephyr/sys/byteorder.h>
 
 #include <zephyr/logging/log.h>
@@ -475,7 +476,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
 	if (err != 0 && role == ROLE_CENTRAL) {
-		LOG_INF("Failed to connect to %s: %u", addr, err);
+		LOG_INF("Failed to connect to %s: %u %s", addr, err, bt_hci_err_to_str(err));
 
 		bt_conn_unref(default_conn);
 		default_conn = NULL;
@@ -495,7 +496,7 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
-	LOG_INF("Disconnected: %s (reason 0x%02x)", addr, reason);
+	LOG_INF("Disconnected: %s, reason 0x%02x %s", addr, reason, bt_hci_err_to_str(reason));
 
 	bt_conn_unref(default_conn);
 	default_conn = NULL;
diff --git a/samples/bluetooth/mtu_update/central/src/central_mtu_update.c b/samples/bluetooth/mtu_update/central/src/central_mtu_update.c
index 9db4b507d3c..d1d8f93cf07 100644
--- a/samples/bluetooth/mtu_update/central/src/central_mtu_update.c
+++ b/samples/bluetooth/mtu_update/central/src/central_mtu_update.c
@@ -194,7 +194,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
 	if (err) {
-		printk("Failed to connect to %s (%u)\n", addr, err);
+		printk("Failed to connect to %s %u %s\n", addr, err, bt_hci_err_to_str(err));
 
 		bt_conn_unref(default_conn);
 		default_conn = NULL;
@@ -233,7 +233,7 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
-	printk("Disconnected: %s (reason 0x%02x)\n", addr, reason);
+	printk("Disconnected: %s, reason 0x%02x %s\n", addr, reason, bt_hci_err_to_str(reason));
 
 	bt_conn_unref(default_conn);
 	default_conn = NULL;
diff --git a/samples/bluetooth/periodic_adv_conn/src/main.c b/samples/bluetooth/periodic_adv_conn/src/main.c
index 1bfcc55977a..49c1c522f14 100644
--- a/samples/bluetooth/periodic_adv_conn/src/main.c
+++ b/samples/bluetooth/periodic_adv_conn/src/main.c
@@ -7,6 +7,7 @@
 #include <zephyr/bluetooth/bluetooth.h>
 #include <zephyr/bluetooth/conn.h>
 #include <zephyr/bluetooth/gap.h>
+#include <zephyr/bluetooth/hci.h>
 
 #define NUM_RSP_SLOTS	  5
 #define NUM_SUBEVENTS	  5
@@ -133,7 +134,7 @@ static void connected_cb(struct bt_conn *conn, uint8_t err)
 
 static void disconnected_cb(struct bt_conn *conn, uint8_t reason)
 {
-	printk("Disconnected (reason 0x%02X)\n", reason);
+	printk("Disconnected, reason 0x%02X %s\n", reason, bt_hci_err_to_str(reason));
 
 	__ASSERT(conn == default_conn, "Unexpected disconnected callback");
 
diff --git a/samples/bluetooth/periodic_adv_rsp/src/main.c b/samples/bluetooth/periodic_adv_rsp/src/main.c
index e20c07660b1..7595aa3ca1a 100644
--- a/samples/bluetooth/periodic_adv_rsp/src/main.c
+++ b/samples/bluetooth/periodic_adv_rsp/src/main.c
@@ -8,6 +8,7 @@
 #include <zephyr/bluetooth/bluetooth.h>
 #include <zephyr/bluetooth/conn.h>
 #include <zephyr/bluetooth/gatt.h>
+#include <zephyr/bluetooth/hci.h>
 
 #define NUM_RSP_SLOTS 5
 #define NUM_SUBEVENTS 5
@@ -116,7 +117,7 @@ void connected_cb(struct bt_conn *conn, uint8_t err)
 
 void disconnected_cb(struct bt_conn *conn, uint8_t reason)
 {
-	printk("Disconnected (reason 0x%02X)\n", reason);
+	printk("Disconnected, reason 0x%02X %s\n", reason, bt_hci_err_to_str(reason));
 
 	bt_conn_unref(default_conn);
 	default_conn = NULL;
diff --git a/samples/bluetooth/periodic_sync_conn/src/main.c b/samples/bluetooth/periodic_sync_conn/src/main.c
index c5b964b1c95..db858ef351c 100644
--- a/samples/bluetooth/periodic_sync_conn/src/main.c
+++ b/samples/bluetooth/periodic_sync_conn/src/main.c
@@ -7,6 +7,7 @@
 #include <zephyr/bluetooth/bluetooth.h>
 #include <zephyr/bluetooth/conn.h>
 #include <zephyr/bluetooth/gap.h>
+#include <zephyr/bluetooth/hci.h>
 #include <zephyr/sys/util.h>
 
 #define NAME_LEN 30
@@ -127,7 +128,7 @@ static void disconnected_cb(struct bt_conn *conn, uint8_t reason)
 	bt_conn_unref(default_conn);
 	default_conn = NULL;
 
-	printk("Disconnected (reason 0x%02X)\n", reason);
+	printk("Disconnected, reason 0x%02X %s\n", reason, bt_hci_err_to_str(reason));
 
 	k_sem_give(&sem_disconnected);
 }
diff --git a/samples/bluetooth/periodic_sync_rsp/src/main.c b/samples/bluetooth/periodic_sync_rsp/src/main.c
index 462c1e28034..013e7a28e50 100644
--- a/samples/bluetooth/periodic_sync_rsp/src/main.c
+++ b/samples/bluetooth/periodic_sync_rsp/src/main.c
@@ -8,6 +8,7 @@
 #include <zephyr/bluetooth/conn.h>
 #include <zephyr/bluetooth/gatt.h>
 #include <zephyr/bluetooth/uuid.h>
+#include <zephyr/bluetooth/hci.h>
 #include <zephyr/sys/util.h>
 
 #define NAME_LEN 30
@@ -175,7 +176,7 @@ BT_GATT_SERVICE_DEFINE(pawr_svc, BT_GATT_PRIMARY_SERVICE(&pawr_svc_uuid.uuid),
 
 void connected(struct bt_conn *conn, uint8_t err)
 {
-	printk("Connected (err 0x%02X)\n", err);
+	printk("Connected, err 0x%02X %s\n", err, bt_hci_err_to_str(err));
 
 	if (err) {
 		default_conn = NULL;
@@ -191,7 +192,7 @@ void disconnected(struct bt_conn *conn, uint8_t reason)
 	bt_conn_unref(default_conn);
 	default_conn = NULL;
 
-	printk("Disconnected (reason 0x%02X)\n", reason);
+	printk("Disconnected, reason 0x%02X %s\n", reason, bt_hci_err_to_str(reason));
 }
 
 BT_CONN_CB_DEFINE(conn_cb) = {
diff --git a/samples/bluetooth/peripheral/src/main.c b/samples/bluetooth/peripheral/src/main.c
index 1abc19166d2..d645ad3321d 100644
--- a/samples/bluetooth/peripheral/src/main.c
+++ b/samples/bluetooth/peripheral/src/main.c
@@ -242,7 +242,7 @@ static struct bt_gatt_cb gatt_callbacks = {
 static void connected(struct bt_conn *conn, uint8_t err)
 {
 	if (err) {
-		printk("Connection failed (err 0x%02x)\n", err);
+		printk("Connection failed, err 0x%02x %s\n", err, bt_hci_err_to_str(err));
 	} else {
 		printk("Connected\n");
 	}
@@ -250,7 +250,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 
 static void disconnected(struct bt_conn *conn, uint8_t reason)
 {
-	printk("Disconnected (reason 0x%02x)\n", reason);
+	printk("Disconnected, reason 0x%02x %s\n", reason, bt_hci_err_to_str(reason));
 }
 
 static void alert_stop(void)
diff --git a/samples/bluetooth/peripheral_accept_list/src/main.c b/samples/bluetooth/peripheral_accept_list/src/main.c
index 6add0de5d66..ee32add74cf 100644
--- a/samples/bluetooth/peripheral_accept_list/src/main.c
+++ b/samples/bluetooth/peripheral_accept_list/src/main.c
@@ -14,6 +14,7 @@
 #include <zephyr/bluetooth/conn.h>
 #include <zephyr/bluetooth/uuid.h>
 #include <zephyr/bluetooth/gatt.h>
+#include <zephyr/bluetooth/hci.h>
 
 /* Custom Service Variables */
 #define BT_UUID_CUSTOM_SERVICE_VAL \
@@ -81,7 +82,7 @@ static const struct bt_data sd[] = {
 static void connected(struct bt_conn *conn, uint8_t err)
 {
 	if (err) {
-		printk("Connection failed (err 0x%02x)\n", err);
+		printk("Connection failed, err 0x%02x %s\n", err, bt_hci_err_to_str(err));
 	} else {
 		printk("Connected\n");
 	}
@@ -89,7 +90,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 
 static void disconnected(struct bt_conn *conn, uint8_t reason)
 {
-	printk("Disconnected (reason 0x%02x)\n", reason);
+	printk("Disconnected, reason 0x%02x %s\n", reason, bt_hci_err_to_str(reason));
 }
 
 BT_CONN_CB_DEFINE(conn_callbacks) = {
diff --git a/samples/bluetooth/peripheral_csc/src/main.c b/samples/bluetooth/peripheral_csc/src/main.c
index cdedeca2fc4..aeb7a71ecdd 100644
--- a/samples/bluetooth/peripheral_csc/src/main.c
+++ b/samples/bluetooth/peripheral_csc/src/main.c
@@ -21,6 +21,7 @@
 #include <zephyr/bluetooth/conn.h>
 #include <zephyr/bluetooth/uuid.h>
 #include <zephyr/bluetooth/gatt.h>
+#include <zephyr/bluetooth/hci.h>
 #include <zephyr/bluetooth/services/bas.h>
 
 #define CSC_SUPPORTED_LOCATIONS		{ CSC_LOC_OTHER, \
@@ -345,7 +346,7 @@ static void csc_simulation(void)
 static void connected(struct bt_conn *conn, uint8_t err)
 {
 	if (err) {
-		printk("Connection failed (err 0x%02x)\n", err);
+		printk("Connection failed, err 0x%02x %s\n", err, bt_hci_err_to_str(err));
 	} else {
 		printk("Connected\n");
 	}
@@ -353,7 +354,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 
 static void disconnected(struct bt_conn *conn, uint8_t reason)
 {
-	printk("Disconnected (reason 0x%02x)\n", reason);
+	printk("Disconnected, reason 0x%02x %s\n", reason, bt_hci_err_to_str(reason));
 }
 
 BT_CONN_CB_DEFINE(conn_callbacks) = {
diff --git a/samples/bluetooth/peripheral_dis/src/main.c b/samples/bluetooth/peripheral_dis/src/main.c
index b20f7f3748b..324602de30d 100644
--- a/samples/bluetooth/peripheral_dis/src/main.c
+++ b/samples/bluetooth/peripheral_dis/src/main.c
@@ -33,7 +33,7 @@ static const struct bt_data sd[] = {
 static void connected(struct bt_conn *conn, uint8_t err)
 {
 	if (err) {
-		printk("Connection failed (err 0x%02x)\n", err);
+		printk("Connection failed, err 0x%02x %s\n", err, bt_hci_err_to_str(err));
 	} else {
 		printk("Connected\n");
 	}
@@ -41,7 +41,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 
 static void disconnected(struct bt_conn *conn, uint8_t reason)
 {
-	printk("Disconnected (reason 0x%02x)\n", reason);
+	printk("Disconnected, reason 0x%02x %s\n", reason, bt_hci_err_to_str(reason));
 }
 
 BT_CONN_CB_DEFINE(conn_callbacks) = {
diff --git a/samples/bluetooth/peripheral_esp/src/main.c b/samples/bluetooth/peripheral_esp/src/main.c
index 6a2d40f9b12..b71ff7ed154 100644
--- a/samples/bluetooth/peripheral_esp/src/main.c
+++ b/samples/bluetooth/peripheral_esp/src/main.c
@@ -399,7 +399,7 @@ static const struct bt_data sd[] = {
 static void connected(struct bt_conn *conn, uint8_t err)
 {
 	if (err) {
-		printk("Connection failed (err 0x%02x)\n", err);
+		printk("Connection failed, err 0x%02x %s\n", err, bt_hci_err_to_str(err));
 	} else {
 		printk("Connected\n");
 	}
@@ -407,7 +407,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 
 static void disconnected(struct bt_conn *conn, uint8_t reason)
 {
-	printk("Disconnected (reason 0x%02x)\n", reason);
+	printk("Disconnected, reason 0x%02x %s\n", reason, bt_hci_err_to_str(reason));
 }
 
 BT_CONN_CB_DEFINE(conn_callbacks) = {
diff --git a/samples/bluetooth/peripheral_gatt_write/src/peripheral_gatt_write.c b/samples/bluetooth/peripheral_gatt_write/src/peripheral_gatt_write.c
index 41bb65988cb..0e0d082004b 100644
--- a/samples/bluetooth/peripheral_gatt_write/src/peripheral_gatt_write.c
+++ b/samples/bluetooth/peripheral_gatt_write/src/peripheral_gatt_write.c
@@ -10,6 +10,7 @@
 #include <zephyr/bluetooth/bluetooth.h>
 #include <zephyr/bluetooth/conn.h>
 #include <zephyr/bluetooth/gatt.h>
+#include <zephyr/bluetooth/hci.h>
 
 extern int mtu_exchange(struct bt_conn *conn);
 extern int write_cmd(struct bt_conn *conn);
diff --git a/samples/bluetooth/peripheral_hids/src/main.c b/samples/bluetooth/peripheral_hids/src/main.c
index 92e60744fe9..25e82c346e8 100644
--- a/samples/bluetooth/peripheral_hids/src/main.c
+++ b/samples/bluetooth/peripheral_hids/src/main.c
@@ -42,7 +42,8 @@ static void connected(struct bt_conn *conn, uint8_t err)
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
 	if (err) {
-		printk("Failed to connect to %s (%u)\n", addr, err);
+		printk("Failed to connect to %s, err 0x%02x %s\n", addr,
+		       err, bt_hci_err_to_str(err));
 		return;
 	}
 
@@ -59,7 +60,8 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
-	printk("Disconnected from %s (reason 0x%02x)\n", addr, reason);
+	printk("Disconnected from %s, reason 0x%02x %s\n", addr,
+	       reason, bt_hci_err_to_str(reason));
 }
 
 static void security_changed(struct bt_conn *conn, bt_security_t level,
@@ -72,8 +74,8 @@ static void security_changed(struct bt_conn *conn, bt_security_t level,
 	if (!err) {
 		printk("Security changed: %s level %u\n", addr, level);
 	} else {
-		printk("Security failed: %s level %u err %d\n", addr, level,
-		       err);
+		printk("Security failed: %s level %u err %s(%d)\n", addr, level,
+		       bt_security_err_to_str(err), err);
 	}
 }
 
diff --git a/samples/bluetooth/peripheral_hr/src/main.c b/samples/bluetooth/peripheral_hr/src/main.c
index 5081d93a64b..8d7f73e5440 100644
--- a/samples/bluetooth/peripheral_hr/src/main.c
+++ b/samples/bluetooth/peripheral_hr/src/main.c
@@ -46,7 +46,7 @@ static ATOMIC_DEFINE(state, 2U);
 static void connected(struct bt_conn *conn, uint8_t err)
 {
 	if (err) {
-		printk("Connection failed (err 0x%02x)\n", err);
+		printk("Connection failed, err 0x%02x %s\n", err, bt_hci_err_to_str(err));
 	} else {
 		printk("Connected\n");
 
@@ -56,7 +56,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 
 static void disconnected(struct bt_conn *conn, uint8_t reason)
 {
-	printk("Disconnected (reason 0x%02x)\n", reason);
+	printk("Disconnected, reason 0x%02x %s\n", reason, bt_hci_err_to_str(reason));
 
 	(void)atomic_set_bit(state, STATE_DISCONNECTED);
 }
diff --git a/samples/bluetooth/peripheral_ht/src/main.c b/samples/bluetooth/peripheral_ht/src/main.c
index 704bad983b2..b3bffc30e4f 100644
--- a/samples/bluetooth/peripheral_ht/src/main.c
+++ b/samples/bluetooth/peripheral_ht/src/main.c
@@ -38,7 +38,7 @@ static const struct bt_data sd[] = {
 static void connected(struct bt_conn *conn, uint8_t err)
 {
 	if (err) {
-		printk("Connection failed (err 0x%02x)\n", err);
+		printk("Connection failed, err 0x%02x %s\n", err, bt_hci_err_to_str(err));
 	} else {
 		printk("Connected\n");
 	}
@@ -46,7 +46,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 
 static void disconnected(struct bt_conn *conn, uint8_t reason)
 {
-	printk("Disconnected (reason 0x%02x)\n", reason);
+	printk("Disconnected, reason 0x%02x %s\n", reason, bt_hci_err_to_str(reason));
 }
 
 BT_CONN_CB_DEFINE(conn_callbacks) = {
diff --git a/samples/bluetooth/peripheral_identity/src/peripheral_identity.c b/samples/bluetooth/peripheral_identity/src/peripheral_identity.c
index 57956081fe3..52d71e642a3 100644
--- a/samples/bluetooth/peripheral_identity/src/peripheral_identity.c
+++ b/samples/bluetooth/peripheral_identity/src/peripheral_identity.c
@@ -12,6 +12,7 @@
 
 #include <zephyr/bluetooth/bluetooth.h>
 #include <zephyr/bluetooth/conn.h>
+#include <zephyr/bluetooth/hci.h>
 
 static struct k_work work_adv_start;
 static uint8_t volatile conn_count;
@@ -79,7 +80,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 	char addr[BT_ADDR_LE_STR_LEN];
 
 	if (err) {
-		printk("Connection failed (err 0x%02x)\n", err);
+		printk("Connection failed, err 0x%02x %s\n", err, bt_hci_err_to_str(err));
 		return;
 	}
 
@@ -99,7 +100,7 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
-	printk("Disconnected %s (reason 0x%02x)\n", addr, reason);
+	printk("Disconnected %s, reason %s(0x%02x)\n", addr, bt_hci_err_to_str(reason), reason);
 
 	if ((conn_count == 1U) && is_disconnecting) {
 		is_disconnecting = false;
@@ -170,8 +171,8 @@ static void security_changed(struct bt_conn *conn, bt_security_t level,
 	if (!err) {
 		printk("Security changed: %s level %u\n", addr, level);
 	} else {
-		printk("Security failed: %s level %u err %d\n", addr, level,
-		       err);
+		printk("Security failed: %s level %u err %s(%d)\n", addr, level,
+		       bt_security_err_to_str(err), err);
 	}
 }
 
diff --git a/samples/bluetooth/peripheral_iso/src/main.c b/samples/bluetooth/peripheral_iso/src/main.c
index 7af0208216b..3ce6f688e84 100644
--- a/samples/bluetooth/peripheral_iso/src/main.c
+++ b/samples/bluetooth/peripheral_iso/src/main.c
@@ -33,7 +33,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
 	if (err) {
-		printk("Failed to connect to %s (%u)\n", addr, err);
+		printk("Failed to connect to %s %u %s\n", addr, err, bt_hci_err_to_str(err));
 		return;
 	}
 
@@ -46,7 +46,8 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
-	printk("Disconnected from %s (reason 0x%02x)\n", addr, reason);
+	printk("Disconnected from %s, reason 0x%02x %s\n", addr,
+	       reason, bt_hci_err_to_str(reason));
 }
 
 BT_CONN_CB_DEFINE(conn_callbacks) = {
diff --git a/samples/bluetooth/peripheral_ots/src/main.c b/samples/bluetooth/peripheral_ots/src/main.c
index f6d92f0b5ca..f3e70c2e8ce 100644
--- a/samples/bluetooth/peripheral_ots/src/main.c
+++ b/samples/bluetooth/peripheral_ots/src/main.c
@@ -13,6 +13,7 @@
 #include <zephyr/bluetooth/bluetooth.h>
 #include <zephyr/bluetooth/conn.h>
 #include <zephyr/bluetooth/gatt.h>
+#include <zephyr/bluetooth/hci.h>
 
 #include <zephyr/bluetooth/services/ots.h>
 
@@ -50,7 +51,7 @@ static struct object_creation_data *object_being_created;
 static void connected(struct bt_conn *conn, uint8_t err)
 {
 	if (err) {
-		printk("Connection failed (err %u)\n", err);
+		printk("Connection failed, err %u %s\n", err, bt_hci_err_to_str(err));
 		return;
 	}
 
@@ -59,7 +60,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 
 static void disconnected(struct bt_conn *conn, uint8_t reason)
 {
-	printk("Disconnected (reason %u)\n", reason);
+	printk("Disconnected, reason %u %s\n", reason, bt_hci_err_to_str(reason));
 }
 
 BT_CONN_CB_DEFINE(conn_callbacks) = {
diff --git a/samples/bluetooth/peripheral_past/src/main.c b/samples/bluetooth/peripheral_past/src/main.c
index 5ed4e864e80..9461b28b2f9 100644
--- a/samples/bluetooth/peripheral_past/src/main.c
+++ b/samples/bluetooth/peripheral_past/src/main.c
@@ -9,6 +9,7 @@
 #include <zephyr/drivers/gpio.h>
 #include <zephyr/bluetooth/bluetooth.h>
 #include <zephyr/bluetooth/conn.h>
+#include <zephyr/bluetooth/hci.h>
 
 static struct bt_conn *default_conn;
 
@@ -99,7 +100,7 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
-	printk("Disconnected: %s (reason 0x%02x)\n", addr, reason);
+	printk("Disconnected: %s, reason 0x%02x %s\n", addr, reason, bt_hci_err_to_str(reason));
 
 	bt_conn_unref(default_conn);
 	default_conn = NULL;
diff --git a/samples/bluetooth/peripheral_sc_only/src/main.c b/samples/bluetooth/peripheral_sc_only/src/main.c
index dae77354098..91cc46a385a 100644
--- a/samples/bluetooth/peripheral_sc_only/src/main.c
+++ b/samples/bluetooth/peripheral_sc_only/src/main.c
@@ -35,7 +35,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
 	if (err) {
-		printk("Failed to connect to %s (%u)\n", addr, err);
+		printk("Failed to connect to %s %u %s\n", addr, err, bt_hci_err_to_str(err));
 		return;
 	}
 
@@ -52,7 +52,8 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
-	printk("Disconnected from %s (reason 0x%02x)\n", addr, reason);
+	printk("Disconnected from %s, reason 0x%02x %s\n", addr,
+	       reason, bt_hci_err_to_str(reason));
 }
 
 static void identity_resolved(struct bt_conn *conn, const bt_addr_le_t *rpa,
@@ -77,8 +78,8 @@ static void security_changed(struct bt_conn *conn, bt_security_t level,
 	if (!err) {
 		printk("Security changed: %s level %u\n", addr, level);
 	} else {
-		printk("Security failed: %s level %u err %d\n", addr, level,
-		       err);
+		printk("Security failed: %s level %u err %s(%d)\n", addr, level,
+		       bt_security_err_to_str(err), err);
 	}
 }
 
diff --git a/samples/bluetooth/st_ble_sensor/src/main.c b/samples/bluetooth/st_ble_sensor/src/main.c
index 515b1ab6166..de287b61167 100644
--- a/samples/bluetooth/st_ble_sensor/src/main.c
+++ b/samples/bluetooth/st_ble_sensor/src/main.c
@@ -170,7 +170,7 @@ static void disconnected(struct bt_conn *disconn, uint8_t reason)
 		ble_conn = NULL;
 	}
 
-	LOG_INF("Disconnected (reason %u)", reason);
+	LOG_INF("Disconnected, reason %u %s", reason, bt_hci_err_to_str(reason));
 }
 
 BT_CONN_CB_DEFINE(conn_callbacks) = {
diff --git a/samples/bluetooth/tmap_central/src/main.c b/samples/bluetooth/tmap_central/src/main.c
index fa75817c8f9..6910feab9e5 100644
--- a/samples/bluetooth/tmap_central/src/main.c
+++ b/samples/bluetooth/tmap_central/src/main.c
@@ -18,6 +18,7 @@
 #include <zephyr/bluetooth/audio/bap_lc3_preset.h>
 #include <zephyr/bluetooth/audio/tmap.h>
 #include <zephyr/bluetooth/audio/cap.h>
+#include <zephyr/bluetooth/hci.h>
 
 #include "tmap_central.h"
 
@@ -82,7 +83,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 	(void)bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
 	if (err != 0) {
-		printk("Failed to connect to %s (%u)\n", addr, err);
+		printk("Failed to connect to %s %u %s\n", addr, err, bt_hci_err_to_str(err));
 
 		bt_conn_unref(default_conn);
 		default_conn = NULL;
@@ -109,7 +110,7 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 
 	(void)bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
-	printk("Disconnected: %s (reason 0x%02x)\n", addr, reason);
+	printk("Disconnected: %s, reason 0x%02x %s\n", addr, reason, bt_hci_err_to_str(reason));
 
 	bt_conn_unref(default_conn);
 	default_conn = NULL;
@@ -124,7 +125,7 @@ static void security_changed(struct bt_conn *conn, bt_security_t level,
 		printk("Security changed: %u\n", err);
 		k_sem_give(&sem_security_updated);
 	} else {
-		printk("Failed to set security level: %u\n", err);
+		printk("Failed to set security level: %s(%u)\n", bt_security_err_to_str(err), err);
 	}
 }
 
diff --git a/samples/bluetooth/tmap_central/src/vcp_vol_ctlr.c b/samples/bluetooth/tmap_central/src/vcp_vol_ctlr.c
index f398f406878..b528aa52a56 100644
--- a/samples/bluetooth/tmap_central/src/vcp_vol_ctlr.c
+++ b/samples/bluetooth/tmap_central/src/vcp_vol_ctlr.c
@@ -7,6 +7,7 @@
 #include <zephyr/bluetooth/bluetooth.h>
 #include <zephyr/bluetooth/audio/audio.h>
 #include <zephyr/bluetooth/audio/vcp.h>
+#include <zephyr/bluetooth/hci.h>
 
 static struct bt_vcp_vol_ctlr *vcp_vol_ctlr;
 
@@ -78,7 +79,7 @@ static int process_profile_connection(struct bt_conn *conn)
 static void connected(struct bt_conn *conn, uint8_t err)
 {
 	if (err) {
-		printk("Connection failed (err %d)\n", err);
+		printk("Connection failed, err %d %s\n", err, bt_hci_err_to_str(err));
 		return;
 	}
 
diff --git a/samples/bluetooth/tmap_peripheral/src/main.c b/samples/bluetooth/tmap_peripheral/src/main.c
index 2a7ecc61759..af6076ec3db 100644
--- a/samples/bluetooth/tmap_peripheral/src/main.c
+++ b/samples/bluetooth/tmap_peripheral/src/main.c
@@ -14,6 +14,7 @@
 #include <zephyr/bluetooth/bluetooth.h>
 #include <zephyr/bluetooth/byteorder.h>
 #include <zephyr/bluetooth/conn.h>
+#include <zephyr/bluetooth/hci.h>
 #include <zephyr/bluetooth/audio/audio.h>
 #include <zephyr/bluetooth/audio/bap.h>
 #include <zephyr/bluetooth/audio/bap_lc3_preset.h>
@@ -98,7 +99,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
 	if (err != 0) {
-		printk("Failed to connect to %s (%u)\n", addr, err);
+		printk("Failed to connect to %s %u %s\n", addr, err, bt_hci_err_to_str(err));
 
 		default_conn = NULL;
 		return;
@@ -119,7 +120,7 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 
 	bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));
 
-	printk("Disconnected: %s (reason 0x%02x)\n", addr, reason);
+	printk("Disconnected: %s, reason 0x%02x %s\n", addr, reason, bt_hci_err_to_str(reason));
 
 	bt_conn_unref(default_conn);
 	default_conn = NULL;
@@ -134,7 +135,7 @@ static void security_changed(struct bt_conn *conn, bt_security_t level,
 		printk("Security changed: %u\n", err);
 		k_sem_give(&sem_security_updated);
 	} else {
-		printk("Failed to set security level: %u", err);
+		printk("Failed to set security level: %s(%u)", bt_security_err_to_str(err), err);
 	}
 }
 
diff --git a/samples/boards/bbc_microbit/pong/src/ble.c b/samples/boards/bbc_microbit/pong/src/ble.c
index c1da7af5b3f..3601c356126 100644
--- a/samples/boards/bbc_microbit/pong/src/ble.c
+++ b/samples/boards/bbc_microbit/pong/src/ble.c
@@ -235,7 +235,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 	struct bt_conn_info info;
 
 	if (err) {
-		printk("Connection failed (err 0x%02x)\n", err);
+		printk("Connection failed, err 0x%02x %s\n", err, bt_hci_err_to_str(err));
 		return;
 	}
 
@@ -260,7 +260,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 
 static void disconnected(struct bt_conn *conn, uint8_t reason)
 {
-	printk("Disconnected (reason 0x%02x)\n", reason);
+	printk("Disconnected, reason 0x%02x %s\n", reason, bt_hci_err_to_str(reason));
 
 	if (default_conn) {
 		bt_conn_unref(default_conn);
diff --git a/samples/boards/reel_board/mesh_badge/src/main.c b/samples/boards/reel_board/mesh_badge/src/main.c
index 3442a7851aa..33189b8bb62 100644
--- a/samples/boards/reel_board/mesh_badge/src/main.c
+++ b/samples/boards/reel_board/mesh_badge/src/main.c
@@ -14,6 +14,7 @@
 #include <zephyr/bluetooth/bluetooth.h>
 #include <zephyr/bluetooth/gatt.h>
 #include <zephyr/drivers/sensor.h>
+#include <zephyr/bluetooth/hci.h>
 
 #include "mesh.h"
 #include "board.h"
@@ -137,7 +138,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 
 static void disconnected(struct bt_conn *conn, uint8_t reason)
 {
-	printk("Disconnected (reason 0x%02x)\n", reason);
+	printk("Disconnected, reason 0x%02x %s\n", reason, bt_hci_err_to_str(reason));
 
 	if (strcmp(CONFIG_BT_DEVICE_NAME, bt_get_name()) &&
 	    !mesh_is_initialized()) {
diff --git a/samples/subsys/logging/ble_backend/src/main.c b/samples/subsys/logging/ble_backend/src/main.c
index 05647be29aa..c8edb8d8838 100644
--- a/samples/subsys/logging/ble_backend/src/main.c
+++ b/samples/subsys/logging/ble_backend/src/main.c
@@ -6,6 +6,7 @@
 
 #include <zephyr/kernel.h>
 #include <zephyr/bluetooth/gatt.h>
+#include <zephyr/bluetooth/hci.h>
 #include <zephyr/logging/log.h>
 #include <zephyr/logging/log_backend_ble.h>
 
@@ -37,7 +38,7 @@ static void start_adv(void)
 static void connected(struct bt_conn *conn, uint8_t err)
 {
 	if (err) {
-		LOG_ERR("Connection failed (err 0x%02x)", err);
+		LOG_ERR("Connection failed, err 0x%02x %s", err, bt_hci_err_to_str(err));
 	} else {
 		LOG_INF("Connected");
 	}
@@ -45,7 +46,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 
 static void disconnected(struct bt_conn *conn, uint8_t reason)
 {
-	LOG_INF("Disconnected (reason 0x%02x)", reason);
+	LOG_INF("Disconnected, reason 0x%02x %s", reason, bt_hci_err_to_str(reason));
 	start_adv();
 }
 
diff --git a/samples/subsys/mgmt/mcumgr/smp_svr/src/bluetooth.c b/samples/subsys/mgmt/mcumgr/smp_svr/src/bluetooth.c
index cdaba854090..2eedfc66911 100644
--- a/samples/subsys/mgmt/mcumgr/smp_svr/src/bluetooth.c
+++ b/samples/subsys/mgmt/mcumgr/smp_svr/src/bluetooth.c
@@ -8,6 +8,7 @@
 #include <zephyr/bluetooth/bluetooth.h>
 #include <zephyr/bluetooth/conn.h>
 #include <zephyr/bluetooth/gatt.h>
+#include <zephyr/bluetooth/hci.h>
 #include <zephyr/mgmt/mcumgr/transport/smp_bt.h>
 
 #define LOG_LEVEL LOG_LEVEL_DBG
@@ -43,7 +44,7 @@ static void advertise(struct k_work *work)
 static void connected(struct bt_conn *conn, uint8_t err)
 {
 	if (err) {
-		LOG_ERR("Connection failed (err 0x%02x)", err);
+		LOG_ERR("Connection failed, err 0x%02x %s", err, bt_hci_err_to_str(err));
 	} else {
 		LOG_INF("Connected");
 	}
@@ -53,7 +54,7 @@ static void connected(struct bt_conn *conn, uint8_t err)
 
 static void disconnected(struct bt_conn *conn, uint8_t reason)
 {
-	LOG_INF("Disconnected (reason 0x%02x)", reason);
+	LOG_INF("Disconnected, reason 0x%02x %s", reason, bt_hci_err_to_str(reason));
 }
 
 static void on_conn_recycled(void)
diff --git a/subsys/bluetooth/shell/bt.c b/subsys/bluetooth/shell/bt.c
index 4801ce564e1..23207a6f5ff 100644
--- a/subsys/bluetooth/shell/bt.c
+++ b/subsys/bluetooth/shell/bt.c
@@ -741,8 +741,8 @@ static void connected(struct bt_conn *conn, uint8_t err)
 	conn_addr_str(conn, addr, sizeof(addr));
 
 	if (err) {
-		shell_error(ctx_shell, "Failed to connect to %s (0x%02x)", addr,
-			     err);
+		shell_error(ctx_shell, "Failed to connect to %s 0x%02x %s", addr,
+			    err, bt_hci_err_to_str(err));
 		goto done;
 	}