diff --git a/homeassistant/components/websocket_api/connection.py b/homeassistant/components/websocket_api/connection.py
index 075aed86453..9b53f358b85 100644
--- a/homeassistant/components/websocket_api/connection.py
+++ b/homeassistant/components/websocket_api/connection.py
@@ -121,6 +121,9 @@ class ActiveConnection:
         """Handle an exception while processing a handler."""
         log_handler = self.logger.error
 
+        code = const.ERR_UNKNOWN_ERROR
+        err_message = None
+
         if isinstance(err, Unauthorized):
             code = const.ERR_UNAUTHORIZED
             err_message = "Unauthorized"
@@ -131,13 +134,15 @@ class ActiveConnection:
             code = const.ERR_TIMEOUT
             err_message = "Timeout"
         elif isinstance(err, HomeAssistantError):
-            code = const.ERR_UNKNOWN_ERROR
             err_message = str(err)
-        else:
-            code = const.ERR_UNKNOWN_ERROR
+
+        # This if-check matches all other errors but also matches errors which
+        # result in an empty message. In that case we will also log the stack
+        # trace so it can be fixed.
+        if not err_message:
             err_message = "Unknown error"
             log_handler = self.logger.exception
 
-        log_handler("Error handling message: %s", err_message)
+        log_handler("Error handling message: %s (%s)", err_message, code)
 
         self.send_message(messages.error_message(msg["id"], code, err_message))
diff --git a/tests/components/websocket_api/test_connection.py b/tests/components/websocket_api/test_connection.py
index 0a9ae710bc5..3a54d5912e0 100644
--- a/tests/components/websocket_api/test_connection.py
+++ b/tests/components/websocket_api/test_connection.py
@@ -54,6 +54,11 @@ async def test_exception_handling():
             "Failed to do X",
         ),
         (ValueError("Really bad"), websocket_api.ERR_UNKNOWN_ERROR, "Unknown error"),
+        (
+            exceptions.HomeAssistantError(),
+            websocket_api.ERR_UNKNOWN_ERROR,
+            "Unknown error",
+        ),
     ):
         send_messages.clear()
         conn.async_handle_exception({"id": 5}, exc)