diff --git a/python/fusion_engine_client/messages/defs.py b/python/fusion_engine_client/messages/defs.py
index 7adce934..8da65312 100644
--- a/python/fusion_engine_client/messages/defs.py
+++ b/python/fusion_engine_client/messages/defs.py
@@ -79,6 +79,8 @@ class Response(IntEnum):
     NO_DATA_STORED = 8
     ## The device is in a state where it can't process the command.
     UNAVAILABLE = 9
+    ## A TransportType specified in the command is invalid, or unsupported on the target device.
+    TRANSPORT_TYPE_ERROR = 10
 
 
 class MessageType(IntEnum):
diff --git a/src/point_one/fusion_engine/messages/defs.h b/src/point_one/fusion_engine/messages/defs.h
index 1737c494..d9235a72 100644
--- a/src/point_one/fusion_engine/messages/defs.h
+++ b/src/point_one/fusion_engine/messages/defs.h
@@ -414,6 +414,11 @@ enum class Response : uint8_t {
    * The device is in a state where it can't process the command.
    */
   UNAVAILABLE = 9,
+  /**
+   * A TransportType specified in the command is invalid, or unsupported on the
+   * target device.
+   */
+  TRANSPORT_TYPE_ERROR = 10,
 };
 
 /**
@@ -445,9 +450,10 @@ P1_CONSTEXPR_FUNC const char* to_string(Response val) {
       return "No Data Stored";
     case Response::UNAVAILABLE:
       return "Device Unavailable";
-    default:
-      return "Unrecognized";
+    case Response::TRANSPORT_TYPE_ERROR:
+      return "TransportType Error";
   }
+  return "Unrecognized";
 }
 
 /**