n8n-io/n8n · error · NodeOperationError

MongoDB connection error

Error message

MongoDB connection error: ${error.message}

What it means

Catch-all around MongoDB chat-memory setup: connecting the client or building the memory threw (bad host/port/credentials/TLS, unreachable server). The client is closed and the underlying driver message is chained to this NodeOperationError.

Solutions

  1. Read the chained driver message to identify the connection failure
  2. Verify host, port, user/password and TLS settings in the MongoDB credential
Defensive patterns

Strategy: try-catch

When it happens

Trigger: Thrown at packages/@n8n/nodes-langchain/nodes/memory/MemoryMongoDbChat/MemoryMongoDbChat.node.ts:168 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of n8n-io/n8n@5ac6606e81 (2026-08-12). Data as JSON: /api/errors/836dba9135c3de66. Report an issue: GitHub.

Appendix: source

Thrown at packages/@n8n/nodes-langchain/nodes/memory/MemoryMongoDbChat/MemoryMongoDbChat.node.ts:168

				memoryKey: 'chat_history',
				chatHistory: mongoDBChatHistory,
				returnMessages: true,
				inputKey: 'input',
				outputKey: 'output',
				k: this.getNodeParameter('contextWindowLength', itemIndex, 5) as number,
			});

			async function closeFunction() {
				await client.close();
			}

			return {
				closeFunction,
				response: logWrapper(memory, this),
			};
		} catch (error) {
			void client.close();
			throw new NodeOperationError(this.getNode(), `MongoDB connection error: ${error.message}`);
		}
	}
}

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