diff --git a/lib/realtime.js b/lib/realtime.js
index 8ff857e..0e9af74 100644
--- a/lib/realtime.js
+++ b/lib/realtime.js
@@ -80,6 +80,8 @@ var updater = setInterval(function () {
         if (note.server.isDirty) {
             if (config.debug) logger.info("updater found dirty note: " + key);
             updateNote(note, function(err, _note) {
+                // handle when note already been clean up
+                if (!notes[key] || !notes[key].server) return callback(null, null);
                 if (!_note) {
                     realtime.io.to(note.id).emit('info', {
                         code: 404
@@ -89,7 +91,9 @@ var updater = setInterval(function () {
                 if (err || !_note) {
                     for (var i = 0, l = note.socks.length; i < l; i++) {
                         var sock = note.socks[i];
-                        sock.disconnect(true);
+                        if (typeof sock !== 'undefined' && sock) {
+                            sock.disconnect(true);
+                        }
                     }
                     return callback(err, null);
                 }
@@ -139,6 +143,7 @@ function updateNote(note, callback) {
     });
 }
 function finishUpdateNote(note, _note, callback) {
+    if (!note || !note.server) return callback(null, null);
     var body = note.server.document;
     var title = models.Note.parseNoteTitle(body);
     title = LZString.compressToBase64(title);
@@ -329,6 +334,16 @@ function connectNextSocket() {
         startConnection(connectionSocketQueue[0]);
 }
 
+function interruptConnection(socket, note, user) {
+    if (note) delete note;
+    if (user) delete user;
+    if (socket)
+        clearSocketQueue(connectionSocketQueue, socket);
+    else
+        connectionSocketQueue.shift();
+    connectNextSocket();
+}
+
 var isConnectionBusy = false;
 var connectionSocketQueue = [];
 var isDisconnectBusy = false;
@@ -337,20 +352,14 @@ var disconnectSocketQueue = [];
 function finishConnection(socket, note, user) {
     // if no valid info provided will drop the client
     if (!socket || !note || !user) {
-        if (note) delete note;
-        if (user) delete user;
-        if (socket)
-            clearSocketQueue(connectionSocketQueue, socket);
-        else
-            connectionSocketQueue.shift();
-        connectNextSocket();
-        return;
+        return interruptConnection(socket, note, user);
     }
     //check view permission
     if (note.permission == 'private') {
         if (socket.request.user && socket.request.user.logged_in && socket.request.user.id == note.owner) {
             //na
         } else {
+            interruptConnection(socket, note, user);
             return failConnection(403, 'connection forbidden', socket);
         }
     }