Resolving MongoDB Server Selection Error: ECONNREFUSED 127.0.0.1:27107

The MongooseServerSelectionError: connect ECONNREFUSED 127.0.0.1:27017 error occurs when Mongoose, a MongoDB object modeling tool, fails to connect to the MongoDB server at the specified address and port. This typically happens due to reasons such as the MongoDB server not running, incorrect connection strings, or network issues. This error disrupts database connectivity, preventing applications from accessing the database, which can halt operations relying on database interactions.

Causes of the Error

Here are the primary reasons for the MongooseServerSelectionError: connect ECONNREFUSED 127.0.0.1:27017 error:

1. MongoDB Server Not Running: Ensure the MongoDB server is started. Use the mongod command to start it.
2. Incorrect Connection String: Verify the connection string is correct. It should match the host and port where MongoDB is running.
3. Network Issues: Check for network problems that might prevent the connection. This includes firewall settings or security groups blocking the port.

Troubleshooting Steps

Here are the steps to diagnose and resolve the ‘mongoserverselectionerror connect econnrefused 127.0.0.1:27017′ error:

1. Check MongoDB Server Status:

   • Ensure MongoDB server is running: sudo service mongod start.
   • Verify server status: sudo service mongod status.

2. Verify Connection Strings:

   • Use explicit local IPv4 address: mongodb://127.0.0.1:27017/.
   • Ensure the database name is correct in the connection string.

3. Ensure Network Stability:

   • Check for network issues or firewall settings blocking the connection.
   • Restart network services if necessary.

4. Check for Lock Files:

   • Remove any lock files: ls /tmp/mongodb-27017* and rm /tmp/mongodb-27017*.

5. Restart MongoDB Server:

   • Restart the server: sudo service mongod restart.

These steps should help you resolve the connection error.

Common Solutions

Here are some common solutions to fix the MongooseServerSelectionError: connect ECONNREFUSED 127.0.0.1:27017 error:

1. Restart the MongoDB server: Ensure that the MongoDB server is running. You can start it using the mongod command.
2. Update connection strings: Replace localhost with 127.0.0.1 in your MongoDB URI. For example, use mongodb://127.0.0.1:27017/ instead of mongodb://localhost:27017/.
3. Configure firewall settings: Check your firewall settings to ensure that the port 27017 is open and accessible. This might involve adding a rule to allow traffic on this port.

These steps should help resolve the connection issue.

Preventive Measures

Here are some preventive measures:

1. Regular Server Maintenance:

   • Ensure MongoDB server is running and accessible.
   • Regularly update MongoDB and Mongoose to the latest versions.

2. Monitoring Tools:

   • Use monitoring tools like MongoDB Atlas, Datadog, or Prometheus to keep track of server health and performance.

3. Proper Configuration Practices:

   • Bind MongoDB to the correct IP address (e.g., 127.0.0.1 for localhost).
   • Avoid using both bindIp and bindIp_all simultaneously.
   • Set appropriate serverSelectionTimeoutMS and socketTimeoutMS values in your Mongoose connection options.

Implementing these measures can help prevent the mongoserverselectionerror connect econnrefused 127 0 0 1 27107 error in the future.

The ‘MongooseServerSelectionError: connect ECONNREFUSED 127.0.0.1:27017’ error

occurs when Mongoose fails to connect to the MongoDB server due to reasons such as the server not running, incorrect connection strings, or network issues.

To resolve this error, ensure the MongoDB server is started, verify correct connection strings, and check for network problems. Common solutions include restarting the MongoDB server, updating connection strings, and configuring firewall settings.

Preventive measures include regular server maintenance, using monitoring tools, and proper configuration practices such as binding MongoDB to the correct IP address and setting appropriate timeout values in Mongoose connection options.