diff --git a/pykirdy/driver/kirdy.py b/pykirdy/driver/kirdy.py
index 7f6aa11..c0ed743 100644
--- a/pykirdy/driver/kirdy.py
+++ b/pykirdy/driver/kirdy.py
@@ -171,7 +171,7 @@ class FilterConfig:
         def _filter_type(self):
             return "Sinc3WithFineODR"
 
-class InvalidCmd(Exception):
+class KirdyCmdError(Exception):
     pass
 
 class Device:
@@ -890,15 +890,15 @@ class Kirdy:
         return json.loads(response[0])
     
     def _response_handling(self, msg, msg_type, sig=None):
-        if msg["msg_type"] in ["InvalidCmd", "InvalidDatatype"]:
-            raise InvalidCmd
-        elif msg["msg_type"] == msg_type:
+        if msg["msg_type"] == msg_type:
             if sig is not None:
                 sig.emit(msg)
         else:
             logging.warn(f"Commands fail to execute. {msg['msg_type']}:{msg['msg']}")
-            if self._err_msg_sig is not None and msg['msg'] is not None:
-                self._err_msg_sig.emit(msg['msg'])
+            if self._err_msg_sig is not None:
+                self._err_msg_sig.emit(f"{msg['msg_type']}:{str(msg['msg'])}")
+            else:
+                raise KirdyCmdError(f"{msg['msg_type']}:{str(msg['msg'])}")
         return msg
 
     async def _send_cmd(self, target, cmd, data=None, msg_type="Acknowledge", sig=None):