Unlike MySQL, MongoDB easily handles large unstructured data in applications like eBay, Metlife, Facebook, Shutterfly, etc.

But while connecting, application users may encounter an error like MongoDB connection timeout.

This error happens due to the wrong MongoDB server setting, bad connection parameters, and much more.

That’s why, at Bobcares, we often get requests from our customers to resolve the “MongoDB connection timeout” error as part of our Server Management Services.

Today, we’ll see how our Support Engineers fix the connection timeout error & its related issues.

What is MongoDB connection timeout?

The connection timeout determines the maximum amount of response time that waits for a connection established by the server.

This value is used when making an initial connection to the MongoDB database.

The default connection timeout value ranges from 1 second to 30 seconds.

For example, if you have the connection timeout set to 30 seconds, your applications will never wait more than 30 seconds for the result.

Top Causes & Fixes: MongoDB connection timeout

Let’s take a closer look at what are the causes & how our Support Engineers fixed them.

1. Incorrect MongoDB Client settings

Recently, one of our customers approached us with a problem regarding the MongoDB connection. When he tried to connect MongoDB using the MongoDB client, it resulted in a server error message box that showed a connection timeout error.

This often happens due to settings in the MongoDB client. When the client takes too much time to connect to the MongoDB server than the preset timeout value, it can result in an error.

The fix involves raising the timeout limits on the MongoDB client. For this, we first check with the customer on the settings that they use on their client. We then compare the values set in the MongoDB server. Depending on the values, we suggest tweaking the variables.

For example, in the case of this customer, it was the timeout that was causing the problem. Therefore, we set the max connection idle time to a higher value and this solved the problem. Now, the user can connect to MongoDB using the MongoDB client.

2. Incorrect Connection Parameters

Often this error happens when there are incorrect settings in the connection parameter. In such cases, we modify the settings by navigating to the database in MongoDB.

For example, we tweak the settings in the database field like this.

MONGO_URI=mongodb://user:password@127.0.0.1:27017/dbname?keepAlive=true&poolSize=30&autoReconnect=true&socketTimeoutMS=360000&connectTimeoutMS=360000

3. Firewall blocks IP

Similarly, a DigitalOcean customer reported to us that after creating the MongoDB he couldn’t connect to the database using Node.js. It resulted in an error like

 message: 'failed to connect to server [droplet_ip:27017] on first connect [MongoError: connection 0 to droplet_ip:27017 timed out]'

This error is most common with MongoDB & happens when the connection gets dropped by the firewall.

So, to solve the problem our Support Engineers opened the firewall settings on the server side and allowed the corresponding IP to allow connections.

[Having trouble with connection timeout in MongoDB? We’ll fix it for you.]

Conclusion

In brief, MongoDB is widely used across various web applications. However, errors like MongoDB connection timeout happen due to incorrect settings in the MongoDB server, bad connection parameters, and much more. Today, we saw how our Support Engineers fixed the timeout error using three different methods.