Connection issues to local MongoDB server from node app

I’m trying to create a simple connection to my MongoDB server from my node application, both hosted locally. However, I keep facing the following error in the STDOUT for the node app before it crashes:

MongoExpiredSessionError: Cannot use a session that has ended

It first looked like I closed a connection and then used it again, but I haven’t closed any connections I opened (testing purposes).
Next, I thought that maybe restarting the node app might work, but it didn’t.
However, if I restart both the node app, and the mongo server, no matter how many times I refresh the route on the browser, I don’t face the error. The error only reoccurs when I kill the node process and relaunch it (without relaunching the mongo server). After that, relaunching node doesn’t make a difference until I relaunch the mongo server too.
Can someone figure out what’s going on?

Hi @Harsh_Narang and welcome in the MongoDB Community :muscle: !

“Session” sounds more like a transaction session than a connection issue to me but I could be wrong. Are you using transactions and sessions in your code?

Cheers,
Maxime.

Hey @MaBeuLux88

I wasn’t sure exactly how sessions in mongoDB worked and the link you shared took me a little bit by surprise.
Then I tried to make an educated guess that the session might refer to an express session. I then changed my code from:

    app.use(session({
        resave: false,
        saveUninitialized:false,
        secret: "irandom secretl"
    }));
    MongoDB.connectDB(function(err) {
      
      var indexRouter = require('./routes/index');
      var usersRouter = require('./routes/users');
      var loginRouter = require('./routes/login');
      var logoutRouter = require('./routes/logout');

      app.use('/', indexRouter);
      app.use('/users', usersRouter);
      app.use('/login', loginRouter);
      app.use('/logout', logoutRouter);
 
      // catch 404 and forward to error handler
      app.use(function(req, res, next) {
        next(createError(404));
      });

      // error handler
      app.use(function(err, req, res, next) {
        // set locals, only providing error in development
        res.locals.message = err.message;
        res.locals.error = req.app.get('env') === 'development' ? err : {};

        // render the error page
        res.status(err.status || 500);
        res.render('error');
      });
    });

to just moving the app.use(‘session’) inside the connectDB call.

Appending to the previous reply (can’t find the edit button), the error has seemingly disappeared. Did you intend for the same to happen?

Very hard to say without actually seeing the code before & after, the actual errors and the conditions for it to happen.

Anyway, I’m glad to hear this solved your issue.
The only “project” I did with Express was a little Hello World 6 years ago: https://github.com/MaBeuLux88/helloworldMongoNode. Maybe this will help but the code is old so maybe some APIs changed in the meantime.

Cheers,
Maxime.

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