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Description

This error indicates that the MongoDB client or server encountered a topology type that is invalid or not recognized for the current operation. It typically occurs when there's a mismatch between the expected database cluster configuration (e.g., standalone, replica set, sharded cluster) and the actual configuration it's trying to connect to or operate within.

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Error Message

Invalid Topology Type

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Known Causes

3 known causes

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Mismatched Connection String

The connection string provided by the client application specifies a topology type (e.g., replica set) that does not match the actual MongoDB deployment type (e.g., standalone instance).

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Client/Driver Topology Expectation

The MongoDB client driver or library is configured to expect a specific topology type that differs from what the MongoDB server is actually running or presenting.

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Incorrect Server Configuration

The MongoDB server itself might be configured with conflicting or incomplete topology settings, leading to an ambiguous or invalid state when clients attempt to discover its configuration.

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Solutions

3 solutions available

1. Validate Replica Set Configuration medium

Ensure replica set members are correctly configured and discoverable by each other.

1

Connect to the primary member of your replica set using the `mongosh` shell.

mongosh mongodb://your_primary_host:27017

2

Check the replica set status to identify any inconsistencies or unreachable members.

rs.status()

3

Review the `mongodb.conf` file on each replica set member to verify the `replication.replSetName` parameter is set correctly and consistently across all members.

replication:
  replSetName: yourReplicaSetName

4

Ensure that all replica set members can resolve each other's hostnames or IP addresses. Check `/etc/hosts` files or DNS configurations if necessary.

ping <other_replica_set_member_hostname>

5

Restart the `mongod` service on any misconfigured members after making corrections.

sudo systemctl restart mongod

2. Correct Sharded Cluster Topology advanced

Verify that all components of a sharded cluster (mongod shards, mongos routers, config servers) are correctly initialized and communicating.

1

For each shard replica set, connect to its primary and run `rs.status()` to confirm the shard replica set is healthy.

mongosh mongodb://your_shard_primary_host:27017

2

Connect to a `mongos` instance and check the cluster status to see if all shards are registered and healthy.

mongosh mongodb://your_mongos_host:27017

3

Run the `sh.status()` command within the `mongos` shell to inspect the sharded cluster's topology, including shard registration and chunk distribution.

sh.status()

4

Verify the `mongos` configuration file (`mongos.conf`) points to the correct config server replica set using the `--configdb` option.

sharding:
  configDB: yourConfigServerReplicaSetName/configHost1:27019,configHost2:27019,configHost3:27019

5

Ensure the config server replica set is healthy and accessible by all `mongos` instances. Restart `mongos` and `mongod` (for shards and config servers) if configuration changes were made.

sudo systemctl restart mongos

3. Re-initialize Replica Set or Sharded Cluster advanced

As a last resort, re-initialize the replica set or sharded cluster to enforce a clean topology.

1

**Warning:** This process can lead to data loss if not performed carefully. Back up your data before proceeding.

2

Stop all `mongod` and `mongos` processes associated with the problematic cluster.

sudo systemctl stop mongod

3

On each member, remove the contents of its data directory.

rm -rf /var/lib/mongodb/*

4

On the primary member (for replica sets) or config servers (for sharded clusters), re-initialize the replica set or sharded cluster configuration.

// For Replica Set Initialization:
rs.initiate({ _id: "yourReplicaSetName", members: [ { _id: 0, host: "host1:27017" }, { _id: 1, host: "host2:27017" } ] })

// For Sharded Cluster Initialization (after config server replica set is up):
sh.initiate()

5

Reconfigure and start each member individually, ensuring they are added to the replica set or sharded cluster correctly.

mongod --replSet yourReplicaSetName --config /etc/mongod.conf
mongos --config /etc/mongos.conf

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Related Errors

5 related errors

MongoDB Error 294: Unsupported Cluster Configuration