diff --git a/etc/emq.conf b/etc/emq.conf
index b8c21dc40..ef05b70e2 100644
--- a/etc/emq.conf
+++ b/etc/emq.conf
@@ -1105,7 +1105,7 @@ listener.ws.external.send_timeout_close = on
 
 ## The TCP send buffer(os kernel) for external MQTT/Websocket connections.
 ##
-## See 'listener.tcp.<name>.sndbuf'
+## See: listener.tcp.<name>.sndbuf
 ##
 ## Value: Bytes
 ## listener.ws.external.sndbuf = 4KB
@@ -1159,7 +1159,7 @@ listener.wss.external.max_clients = 64
 
 ## Mountpoint of the MQTT/Websocket/SSL Listener.
 ##
-## See 'listener.tcp.<name>.mountpoint'
+## See: listener.tcp.<name>.mountpoint
 ##
 ## Value: String
 ## listener.wss.external.mountpoint = inbound/
@@ -1262,14 +1262,14 @@ listener.wss.external.certfile = {{ platform_etc_dir }}/certs/cert.pem
 
 ## TCP backlog for the Websocket/SSL connection.
 ##
-## See 'listener.tcp.<name>.backlog'
+## See listener.tcp.<name>.backlog
 ##
 ## Value: Number >= 0
 listener.wss.external.backlog = 1024
 
 ## The TCP send timeout for the Websocket/SSL connection.
 ##
-## See 'listener.tcp.<name>.send_timeout'
+## See: listener.tcp.<name>.send_timeout
 ##
 ## Value: Duration
 listener.wss.external.send_timeout = 15s
diff --git a/priv/emq.schema b/priv/emq.schema
index 11c45cecb..a70a90f90 100644
--- a/priv/emq.schema
+++ b/priv/emq.schema
@@ -400,7 +400,7 @@ end}.
 {translation,
  "lager.handlers",
  fun(Conf) ->
-    ErrorHandler = case cuttlefish:conf_get("log.error.file", Conf) of
+    ErrorHandler = case cuttlefish:conf_get("log.error.file", Conf, undefined) of
       undefined -> [];
       ErrorFilename -> [{lager_file_backend, [{file, ErrorFilename},
                                               {level, error},
@@ -442,7 +442,6 @@ end}.
                    cuttlefish:conf_get("log.syslog.facility", Conf),
                    cuttlefish:conf_get("log.syslog.level", Conf)]}]
     end,
-
     ConsoleHandlers ++ ErrorHandler ++ InfoHandler ++ SyslogHandler
   end
 }.