MongooseError: Operation users.aggregate() buffering timed out after 10000ms

The error "MongooseError: Operation users.aggregate() buffering timed out after 10000ms" typically indicates that Mongoose is attempting to execute an aggregation query on the users collection, but the operation is timing out after 10 seconds

Solutions:

Check Database Connection

• Ensure that your MongoDB server is running and accessible. Check your connection string and any network issues that might be affecting the connection.

Increase Timeout:

• You can increase the timeout by configuring Mongoose to allow a longer time for operations. Example.

const mongoose = require("mongoose");

let URL ="mongodb://localhost:27017/mydatabase";

let option = {
  autoIndex: true,
  serverSelectionTimeoutMS: 50000 // Increase the timeout to 50 seconds
};

mongoose
  .connect(URL, option)
  .then((res) => {
    console.log("Database Connected");
  })
  .catch((err) => {
    console.log(err);
  });        

Optimize the Aggregation Query:

• Try to optimize your aggregation query to reduce the load on the database. This might include indexing fields involved in the query or breaking down the aggregation into smaller steps.

Handle Buffering Explicitly

Disable buffering in Mongoose so that you get an error immediately if the connection isn’t available:

mongoose.set('bufferCommands', false);        

Check Resource Utilization

• Ensure that your MongoDB server has enough resources (CPU, memory) to handle the queries. Monitor the server's performance during the execution of the aggregation.