diff --git a/homeassistant/components/growatt_server/config_flow.py b/homeassistant/components/growatt_server/config_flow.py
index c4a97a81f0a..11f082f1eab 100644
--- a/homeassistant/components/growatt_server/config_flow.py
+++ b/homeassistant/components/growatt_server/config_flow.py
@@ -6,7 +6,13 @@ from homeassistant import config_entries
 from homeassistant.const import CONF_NAME, CONF_PASSWORD, CONF_URL, CONF_USERNAME
 from homeassistant.core import callback
 
-from .const import CONF_PLANT_ID, DEFAULT_URL, DOMAIN, SERVER_URLS
+from .const import (
+    CONF_PLANT_ID,
+    DEFAULT_URL,
+    DOMAIN,
+    LOGIN_INVALID_AUTH_CODE,
+    SERVER_URLS,
+)
 
 
 class GrowattServerConfigFlow(config_entries.ConfigFlow, domain=DOMAIN):
@@ -45,7 +51,10 @@ class GrowattServerConfigFlow(config_entries.ConfigFlow, domain=DOMAIN):
             self.api.login, user_input[CONF_USERNAME], user_input[CONF_PASSWORD]
         )
 
-        if not login_response["success"] and login_response["errCode"] == "102":
+        if (
+            not login_response["success"]
+            and login_response["msg"] == LOGIN_INVALID_AUTH_CODE
+        ):
             return self._async_show_user_form({"base": "invalid_auth"})
         self.user_id = login_response["user"]["id"]
 
diff --git a/homeassistant/components/growatt_server/const.py b/homeassistant/components/growatt_server/const.py
index e0297de5eff..5425e26c806 100644
--- a/homeassistant/components/growatt_server/const.py
+++ b/homeassistant/components/growatt_server/const.py
@@ -16,3 +16,5 @@ DEFAULT_URL = SERVER_URLS[0]
 DOMAIN = "growatt_server"
 
 PLATFORMS = ["sensor"]
+
+LOGIN_INVALID_AUTH_CODE = "502"
diff --git a/homeassistant/components/growatt_server/sensor.py b/homeassistant/components/growatt_server/sensor.py
index 9f0fa509105..804d4157543 100644
--- a/homeassistant/components/growatt_server/sensor.py
+++ b/homeassistant/components/growatt_server/sensor.py
@@ -37,7 +37,7 @@ from homeassistant.const import (
 )
 from homeassistant.util import Throttle, dt
 
-from .const import CONF_PLANT_ID, DEFAULT_PLANT_ID, DEFAULT_URL
+from .const import CONF_PLANT_ID, DEFAULT_PLANT_ID, DEFAULT_URL, LOGIN_INVALID_AUTH_CODE
 
 _LOGGER = logging.getLogger(__name__)
 
@@ -876,7 +876,10 @@ def get_device_list(api, config):
 
     # Log in to api and fetch first plant if no plant id is defined.
     login_response = api.login(config[CONF_USERNAME], config[CONF_PASSWORD])
-    if not login_response["success"] and login_response["errCode"] == "102":
+    if (
+        not login_response["success"]
+        and login_response["msg"] == LOGIN_INVALID_AUTH_CODE
+    ):
         _LOGGER.error("Username, Password or URL may be incorrect!")
         return
     user_id = login_response["user"]["id"]
diff --git a/tests/components/growatt_server/test_config_flow.py b/tests/components/growatt_server/test_config_flow.py
index db46ed36911..ba52e09296c 100644
--- a/tests/components/growatt_server/test_config_flow.py
+++ b/tests/components/growatt_server/test_config_flow.py
@@ -7,6 +7,7 @@ from homeassistant.components.growatt_server.const import (
     CONF_PLANT_ID,
     DEFAULT_URL,
     DOMAIN,
+    LOGIN_INVALID_AUTH_CODE,
 )
 from homeassistant.const import CONF_PASSWORD, CONF_URL, CONF_USERNAME
 
@@ -61,7 +62,7 @@ async def test_incorrect_login(hass):
 
     with patch(
         "growattServer.GrowattApi.login",
-        return_value={"errCode": "102", "success": False},
+        return_value={"msg": LOGIN_INVALID_AUTH_CODE, "success": False},
     ):
         result = await hass.config_entries.flow.async_configure(
             result["flow_id"], FIXTURE_USER_INPUT