MongoError: E11000 duplicate key error index: sessions.sessions.$sid_1 dup key: { : null }

I get the above mentioned error as soon as more than 1 user tries to login into my system.

I am using MongoStore like this

app.use(express.session({
  key: 'sid',
  secret: 'secret',
  store: new MongoStore({
    db: 'sessions',
    secret: 'mongo store secret!'
  })
});

[micate]

@dhruvasagar 😃

I just confirmed that collection created by connect-mongo has only two indexes by default: _id_ and expires_1. So the sid_1 index mentioned by the error must be created by other session packages.

[gabrielstuff]

same here, db.sessions.drop() fixed it.