n8n-io/n8n · error · Error

Subnode output connections are managed by parent node Subnod

Error message

Subnode output connections are managed by parent node SubnodeConfig

What it means

Thrown by SubnodeInstanceImpl.output() — a subnode's output connections are owned by its parent SubnodeConfig. The method is implemented only to conform to the NodeInstance interface; invoking it is a misuse. Use the parent node's API to express how the subnode is wired.

Source

Thrown at packages/@n8n/workflow-sdk/src/workflow-builder/node-builders/subnode-builders.ts:135

			parameters: config.parameters ?? this.config.parameters,
			credentials: config.credentials ?? this.config.credentials,
		};
		return new SubnodeInstanceImpl(
			this.type,
			this.version,
			mergedConfig,
			this._subnodeType,
			this.id,
			this.name,
		);
	}

	input(_index: number): InputTarget {
		throw new Error('Subnode input connections are managed by parent node SubnodeConfig');
	}

	output(_index: number): OutputSelector<TType, TVersion, TOutput> {
		throw new Error('Subnode output connections are managed by parent node SubnodeConfig');
	}

	then<T extends NodeInstance<string, string, unknown>>(
		_target: T | T[] | InputTarget,
		_outputIndex?: number,
	): NodeChain<NodeInstance<TType, TVersion, TOutput>, T> {
		throw new Error('Subnode connections are managed by parent node SubnodeConfig');
	}

	to<T extends NodeInstance<string, string, unknown>>(
		_target: T | T[] | InputTarget,
		_outputIndex?: number,
	): NodeChain<NodeInstance<TType, TVersion, TOutput>, T> {
		throw new Error('Subnode connections are managed by parent node SubnodeConfig');
	}

	onError<T extends NodeInstance<string, string, unknown>>(_handler: T): this {
		throw new Error('Subnode error handling is managed by parent node SubnodeConfig');

View on GitHub (pinned to 5ac6606e81)

Solutions

1. Express the subnode's output wiring on the parent SubnodeConfig node, not on the subnode.
2. Type-guard against SubnodeInstanceImpl before calling .output().
3. Build connections via the parent's subnode-aware API (e.g. agent.to(...), not tool.output(...).to(...)).

Example fix

// before
const sel = toolNode.output(0); // throws
// after
// wire the agent (parent SubnodeConfig), not the tool
agent.to(nextNode);

if (!(node instanceof SubnodeInstanceImpl)) {
  const out = node.output(0);
}

function isSubnodeInstance(n: unknown): n is SubnodeInstanceImpl {
  return n instanceof SubnodeInstanceImpl;
}

When it happens

Trigger: Calling myTool.output(0) to build a connection chain from a tool node, or generic graph traversal code that calls .output() on every NodeInstance.

Common situations: Reusing a generic chain builder that assumes all nodes expose outputs; mistakenly treating a tool subnode like a top-level node and chaining .output(...).to(...).

Related errors

• Subnode input connections are managed by parent node Subnode
• Subnode connections are managed by parent node SubnodeConfig
• Subnode error handling is managed by parent node SubnodeConf
• Reflector output must be valid JSON
• INVALID_CONNECTION

AI-assisted analysis of n8n-io/n8n@5ac6606e81 (2026-08-12). Data as JSON: /api/errors/39c4d958a8330d1b. Report an issue: GitHub.