Uncaught, unspecified 'error' while running node app

I am a beginner in node.js express.js. (started this morning :-) ) I have included db.js which has my connection details to mongolab and User.js which is my model. Please find the code below. Db.js ``` var mongoose = require('mongoose'); var Schema = mongoose.Schema; module.exports.mongoose = mongoose; module.exports.Schema = Schema; // Connect to cloud database var username = "Ausername" var password = "Apassword"; var address = 'Aaddress'; connect(); // Connect to mongo function connect() { var url = 'mongodb://' + username + ':' + password + address; mongoose.connect(url); } function disconnect() {mongoose.disconnect()} ``` User.js ``` var db = require('../lib/db'); var UserSchema = new db.Schema({ username : {type: String, unique: true} , password : String }) var MyUser = db.mongoose.model('User', UserSchema); // Exports module.exports.addUser = addUser; // Add user to database function addUser(username, password, callback) { var instance = new MyUser(); instance.username = username; instance.password = password; instance.save(function (err) { if (err) { callback(err); } else { callback(null, instance); } }); } ``` And when i run node app, it reports the below error ``` C:\Sripaul\Softwares\NodeJS\Projects\authentication>node app Express server listening on port 3000 C:\Sripaul\Softwares\NodeJS\Projects\authentication\node_modules\mongoose\lib\utils.js:413 throw err; ^ Error: Uncaught, unspecified 'error' event. at NativeConnection.EventEmitter.emit (events.js:68:15) at Model.init (C:\Sripaul\Softwares\NodeJS\Projects\authentication\node_modules\mongoose\lib\model.js:554:31) at exports.tick (C:\Sripaul\Softwares\NodeJS\Projects\authentication\node_modules\mongoose\lib\utils.js:408:16) at Db.ensureIndex (C:\Sripaul\Softwares\NodeJS\Projects\authentication\node_modules\mongoose\node_modules\mongodb\lib\mongodb\db.js:1066:28) at Db.indexInformation (C:\Sripaul\Softwares\NodeJS\Projects\authentication\node_modules\mongoose\node_modules\mongodb\lib\mongodb\db.js:1200:28) at Cursor.toArray (C:\Sripaul\Softwares\NodeJS\Projects\authentication\node_modules\mongoose\node_modules\mongodb\lib\mongodb\cursor.js:124:30) at Cursor.each (C:\Sripaul\Softwares\NodeJS\Projects\authentication\node_modules\mongoose\node_modules\mongodb\lib\mongodb\cursor.js:166:32) at Cursor.nextObject.self.queryRun (C:\Sripaul\Softwares\NodeJS\Projects\authentication\node_modules\mongoose\node_modules\mongodb\lib\mongodb\cursor.js:441:39) at Cursor.close (C:\Sripaul\Softwares\NodeJS\Projects\authentication\node_modules\mongoose\node_modules\mongodb\lib\mongodb\cursor.js:687:5) at Cursor.nextObject.commandHandler (C:\Sripaul\Softwares\NodeJS\Projects\authentication\node_modules\mongoose\node_modules\mongodb\lib\mongodb\cursor.js:441:21) ``` Code in in app.js is as below ``` app.post('/signup', function(req, res) { var username = req.body.username; var password = req.body.password; User.addUser(username, password, function(err, user) { if (err) throw err; res.redirect('/form'); }); }); ``` Can someone please help me resolve it?