problem answer

This is a common error that occurs when you use the connect-mongo module to store sessions in a MongoDB database. It means that you are not providing the correct options to the MongoStore class, which is a tool that helps you store sessions in MongoDB.

According to the link you provided, you are using version 4 of the connect-mongo module, which requires you to provide one of the following options:

mongoUrl: a string that contains the connection URL to your MongoDB database. For example: mongoUrl: 'mongodb://localhost:27017/mydb'.
clientPromise: a promise that resolves to a MongoDB client instance. For example: clientPromise: MongoClient.connect(mongoUrl, mongoOptions).
client: a MongoDB client instance that is already connected to the database. For example: client: MongoClient.

You can find more information about these options on the official documentation of the connect-mongo module.

To fix this error, you need to choose one of these options and pass it to the MongoStore class. For example, if you want to use the mongoUrl option, you can do something like this:

// Import the connect-mongo module
const MongoStore = require('connect-mongo');

// Use the MongoStore.create method to create a MongoStore instance
app.use(session({
  secret: 'mysecretkey',
  store: MongoStore.create({ mongoUrl: 'mongodb://localhost:27017/mydb' })
}));