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Description

This error indicates a problem with the underlying network communication between your application and the MongoDB server, or between MongoDB processes. It typically occurs when a connection cannot be established or is unexpectedly terminated.

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Error Message

Socket Exception

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Known Causes

4 known causes

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Network Connectivity Issues

Firewalls, network misconfigurations, or physical disconnections prevent communication between hosts.

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MongoDB Server Unreachable

The 'mongod' process is not running, crashed, or is not listening on the specified network port.

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Incorrect Connection Parameters

The client application is attempting to connect to the wrong host, IP address, or port number for the MongoDB instance.

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Resource Limits Exceeded

The operating system or MongoDB server has run out of available sockets or file descriptors, preventing new connections.

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Solutions

4 solutions available

1. Verify Network Connectivity to MongoDB Host easy

Ensure the client machine can reach the MongoDB server over the network.

1

From the client machine experiencing the error, attempt to ping the MongoDB server's IP address or hostname.

ping <mongodb_server_ip_or_hostname>

2

If ping fails, check for network firewalls (both on the client and server sides) that might be blocking traffic to the MongoDB port (default 27017). Ensure the firewall rules allow inbound connections to this port on the MongoDB server.

3

Use `telnet` or `nc` (netcat) to test connectivity to the specific MongoDB port.

telnet <mongodb_server_ip_or_hostname> 27017

4

If `telnet` or `nc` fails, re-examine network configurations, VPN settings, or any intermediate network devices that might be preventing the connection.

2. Confirm MongoDB Service is Running and Accessible easy

Verify that the MongoDB server process is active and listening on the correct network interface and port.

1

On the MongoDB server, check the status of the MongoDB service.

sudo systemctl status mongod

2

If the service is not running, start it.

sudo systemctl start mongod

3

Check the MongoDB configuration file (`mongod.conf`, typically located at `/etc/mongod.conf` or `/etc/mongodb.conf`) to confirm the `net.port` and `net.bindIp` settings. Ensure `net.bindIp` is set to `0.0.0.0` to listen on all interfaces, or the specific IP address the client is trying to connect to.

4

Restart the MongoDB service after any configuration changes.

sudo systemctl restart mongod

5

From the MongoDB server itself, try connecting locally to confirm the service is operational.

mongo

3. Review MongoDB Bind IP Address Configuration medium

Ensure MongoDB is configured to listen on the network interface the client is attempting to connect to.

1

Locate your MongoDB configuration file. Common locations include `/etc/mongod.conf` on Linux or within the MongoDB installation directory on Windows.

2

Open the configuration file and look for the `net` section. Ensure the `bindIp` parameter is correctly set. If you want MongoDB to be accessible from any IP address, set it to `0.0.0.0`. If you want it to listen on a specific IP address, provide that IP.

net:
  port: 27017
  bindIp: 0.0.0.0

3

If you are connecting from a different machine, `bindIp: 127.0.0.1` (localhost) will prevent external connections. Change it to `0.0.0.0` or the server's actual IP address.

4

After modifying the configuration file, restart the MongoDB service for the changes to take effect.

sudo systemctl restart mongod

4. Check for Resource Exhaustion on the MongoDB Server advanced

Investigate if the MongoDB server is overloaded with connections or system resources.

1

On the MongoDB server, monitor system resource utilization (CPU, memory, disk I/O). High utilization can lead to connection failures.

top
htop
iostat
vacuum

2

Check the MongoDB logs for any indications of resource contention, such as excessive connection attempts or slow operations.

tail -f /var/log/mongodb/mongod.log

3

Examine the number of active connections to MongoDB. If it's close to the configured limit, consider increasing the `maxIncomingConnections` setting in `mongod.conf` or optimizing your application's connection pooling.

4

If using a replica set, ensure all members are healthy and reachable. A degraded replica set can impact connection availability.

rs.status()

5

Consider scaling up your MongoDB server or optimizing queries and application logic if resource exhaustion is a recurring issue.

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Related Errors

5 related errors

MongoDB Error 9001: Connection Failure