diff --git a/src/include/taler_error_codes.h b/src/include/taler_error_codes.h
index c8a030fac..817dd0eff 100644
--- a/src/include/taler_error_codes.h
+++ b/src/include/taler_error_codes.h
@@ -1179,6 +1179,11 @@ enum TALER_ErrorCode
    */
   TALER_EC_TRACK_TRANSFER_CONFLICTING_REPORTS = 2408,
 
+  /**
+   * The merchant backend had problems in creating the JSON response.
+   */
+  TALER_EC_TRACK_TRANSFER_JSON_RESPONSE_ERROR = 2409,
+
   /**
    * The hash provided in the request of /map/in does not match
    * the contract sent alongside in the same request.