As I said in your comment, essentially Express is receiving connections before the session store is fully connected. The solution is to wait for the connection to occur before allowing your application to start listening.
You can avoid this problem by using a callback on MongoStore creation, or passing in an already active connection.
Example using connect-mongo
's Callback
var sessionStore = new MongoStore({ url: 'someConnectionUrl', db: 'audio-drop' }, function(e) {
var cookieParser = express.cookieParser('waytoblue');
app.use(cookieParser);
app.use(express.session({
store: sessionStore
}));
app.listen();
});
Simple Mongoose Example
var mongoose = require('mongoose');
mongoose.connect('localhost', function(e) {
// If error connecting
if(e) throw e;
var sessionStore = new MongoStore({ mongoose_connection: mongoose.connection }),
cookieParser = express.cookieParser('waytoblue');
app.use(cookieParser);
app.use(express.session({
store: sessionStore
}));
app.listen();
});