Review comments

homeassistant/components/config/entity_registry.py

@@ -1,7 +1,7 @@
 """HTTP views to interact with the entity registry."""
 import voluptuous as vol
 
-from homeassistant.core import callback, split_entity_id
+from homeassistant.core import callback
 from homeassistant.helpers.entity_registry import async_get_registry
 from homeassistant.components import websocket_api
 from homeassistant.components.websocket_api.const import ERR_NOT_FOUND
@@ -106,10 +106,9 @@ async def websocket_update_entity(hass, connection, msg):
 
     if 'new_entity_id' in msg:
         changes['new_entity_id'] = msg['new_entity_id']
-        if (msg['new_entity_id'] in hass.states.async_entity_ids(
-                split_entity_id(msg['new_entity_id'])[0])):
+        if hass.states.get(msg['new_entity_id']) is not None:
             connection.send_message(websocket_api.error_message(
-                msg['id'], ERR_NOT_FOUND, 'Entity is already registered'))
+                msg['id'], 'invalid_info', 'Entity is already registered'))
             return
 
     try: