diff --git a/kasa/exceptions.py b/kasa/exceptions.py
index c0ef23b6a..fb86ef14c 100644
--- a/kasa/exceptions.py
+++ b/kasa/exceptions.py
@@ -53,6 +53,8 @@ class SmartErrorCode(IntEnum):
     HTTP_TRANSPORT_FAILED_ERROR = 1112
     LOGIN_FAILED_ERROR = 1111
     HAND_SHAKE_FAILED_ERROR = 1100
+    #: Real description unknown, seen after an encryption-changing fw upgrade
+    TRANSPORT_UNKNOWN_CREDENTIALS_ERROR = 1003
     TRANSPORT_NOT_AVAILABLE_ERROR = 1002
     CMD_COMMAND_CANCEL_ERROR = 1001
     NULL_TRANSPORT_ERROR = 1000
@@ -111,6 +113,7 @@ class SmartErrorCode(IntEnum):
     SmartErrorCode.LOGIN_FAILED_ERROR,
     SmartErrorCode.AES_DECODE_FAIL_ERROR,
     SmartErrorCode.HAND_SHAKE_FAILED_ERROR,
+    SmartErrorCode.TRANSPORT_UNKNOWN_CREDENTIALS_ERROR,
 ]
 
 SMART_TIMEOUT_ERRORS = [