diff --git a/esphome/components/api/api_connection.cpp b/esphome/components/api/api_connection.cpp
index d67143f298..48d23ecfd0 100644
--- a/esphome/components/api/api_connection.cpp
+++ b/esphome/components/api/api_connection.cpp
@@ -1723,7 +1723,7 @@ void APIConnection::on_home_assistant_state_response(const HomeAssistantStateRes
       copy_len = sizeof(state_buf) - 1;  // Truncate to leave space for null terminator
     }
     if (copy_len > 0) {
-      memcpy(state_buf, msg.state.data(), copy_len);
+      memcpy(state_buf, msg.state.c_str(), copy_len);
     }
     state_buf[copy_len] = '\0';
     it.callback(StringRef(state_buf, copy_len));
diff --git a/esphome/components/esp32_improv/__init__.py b/esphome/components/esp32_improv/__init__.py
index 2e69d400ca..ad2f057163 100644
--- a/esphome/components/esp32_improv/__init__.py
+++ b/esphome/components/esp32_improv/__init__.py
@@ -3,7 +3,7 @@ import esphome.codegen as cg
 from esphome.components import binary_sensor, esp32_ble, improv_base, output
 from esphome.components.esp32_ble import BTLoggers
 import esphome.config_validation as cv
-from esphome.const import CONF_ID, CONF_ON_STATE, CONF_TRIGGER_ID
+from esphome.const import CONF_ID, CONF_ON_START, CONF_ON_STATE, CONF_TRIGGER_ID
 
 AUTO_LOAD = ["esp32_ble_server", "improv_base"]
 CODEOWNERS = ["@jesserockz"]
@@ -15,7 +15,6 @@ CONF_BLE_SERVER_ID = "ble_server_id"
 CONF_IDENTIFY_DURATION = "identify_duration"
 CONF_ON_PROVISIONED = "on_provisioned"
 CONF_ON_PROVISIONING = "on_provisioning"
-CONF_ON_START = "on_start"
 CONF_ON_STOP = "on_stop"
 CONF_STATUS_INDICATOR = "status_indicator"
 CONF_WIFI_TIMEOUT = "wifi_timeout"
diff --git a/esphome/components/voice_assistant/__init__.py b/esphome/components/voice_assistant/__init__.py
index 59c7ec8383..d28c786dd8 100644
--- a/esphome/components/voice_assistant/__init__.py
+++ b/esphome/components/voice_assistant/__init__.py
@@ -11,6 +11,7 @@ from esphome.const import (
     CONF_ON_CLIENT_DISCONNECTED,
     CONF_ON_ERROR,
     CONF_ON_IDLE,
+    CONF_ON_START,
     CONF_SPEAKER,
 )
 
@@ -24,7 +25,6 @@ CONF_ON_INTENT_END = "on_intent_end"
 CONF_ON_INTENT_PROGRESS = "on_intent_progress"
 CONF_ON_INTENT_START = "on_intent_start"
 CONF_ON_LISTENING = "on_listening"
-CONF_ON_START = "on_start"
 CONF_ON_STT_END = "on_stt_end"
 CONF_ON_STT_VAD_END = "on_stt_vad_end"
 CONF_ON_STT_VAD_START = "on_stt_vad_start"
diff --git a/esphome/const.py b/esphome/const.py
index 1d46e81f9d..518247aa60 100644
--- a/esphome/const.py
+++ b/esphome/const.py
@@ -710,6 +710,7 @@ CONF_ON_RELEASE = "on_release"
 CONF_ON_RESPONSE = "on_response"
 CONF_ON_SHUTDOWN = "on_shutdown"
 CONF_ON_SPEED_SET = "on_speed_set"
+CONF_ON_START = "on_start"
 CONF_ON_STATE = "on_state"
 CONF_ON_SUCCESS = "on_success"
 CONF_ON_TAG = "on_tag"