mongodb mongoose connection open callback doesnt get called - mongodb

Question

I have a MEAN project and this is a snippet from my server.js
var db = require('./config/db');
// url : 'mongodb://localhost/cdnserver'
// results are same for 127.0.0.1 or the machines ip
console.log(mongoose.connect(db.url));
mongoose.set('debug', true);
mongoose.connection.on('connected', function () {
console.log('Mongoose default connection open to ' + db.url);
});
// If the connection throws an error
mongoose.connection.on('error',function (err) {
console.log('Mongoose default connection error: ' + err);
});
// When the connection is disconnected
mongoose.connection.on('disconnected', function () {
console.log('Mongoose default connection disconnected');
});
This is a setup that has been working well for over 3 months now. Now I am replicating my whole MEAN stack along with database to other machine. I took a mongodump and did mongorestore. The restored db setup looks fine through mongo from terminal.
However, when starting the server, connection-open callback is not getting called. disconnected and error callbacks are getting called if I stop the mongodb service. How do I debug this further?
I am attaching the console output from both the setups.
Setup 1 :
Mongoose {
connections:
[ NativeConnection {
base: [Circular],
collections: {},
models: {},
replica: false,
hosts: null,
host: 'localhost',
port: 27017,
user: undefined,
pass: undefined,
name: 'cdnserver',
options: [Object],
otherDbs: [],
_readyState: 2,
_closeCalled: false,
_hasOpened: false,
_listening: false,
db: [Object] } ],
plugins: [],
models: {},
modelSchemas: {},
options: { pluralization: true } }
Server up on 80
Mongoose default connection open to mongodb://localhost/cdnserver
1
Mongoose: videos.find({}) { skip: 0, limit: 5, fields: undefined }
Setup 2:
Mongoose {
connections:
[ NativeConnection {
base: [Circular],
collections: {},
models: {},
replica: false,
hosts: null,
host: 'localhost',
port: 27017,
user: undefined,
pass: undefined,
name: 'cdnserver',
options: [Object],
otherDbs: [],
_readyState: 2,
_closeCalled: false,
_hasOpened: false,
_listening: false,
db: [Object] } ],
plugins: [],
models: {},
modelSchemas: {},
options: { pluralization: true } }
Server up on 80
1
1
Mongoose default connection disconnected
Mongoose default connection error: Error: connection closed
cat /var/log/mongodb/mongodb.log shows exactly the same output in both the machines.
Update 1: The setup started working properly out of blue and it stopped again. I am not able to figure out what is making this happen.

Answer 1

I figured it out finally, the new setup was using a newer version of nodejs.
When I moved to 6.x from 7.x it worked fine. I guess the mongoose, node 7, mongodb versions didnt go well together.