n8n-io/n8n · warning

AGENT_NO_SYSTEM_MESSAGE

AGENT_NO_SYSTEM_MESSAGE

Error message

'${node.name}' has no system message. System-level instructions should be in the system message field.

What it means

Warning-level validator issue (code AGENT_NO_SYSTEM_MESSAGE) emitted when an Agent node has no system message — neither options.systemMessage nor params.systemMessage is set, or it is an empty/whitespace string. Without a system message the agent lacks system-level instructions, which usually leads to inconsistent behavior.

Source

Thrown at packages/@n8n/workflow-sdk/src/workflow-builder/plugins/validators/agent-validator.ts:67

		// (MISSING_EXPRESSION_PREFIX will handle malformed expressions)
		if (!text || (!hasValidExpression && !hasMalformedExpression)) {
			issues.push({
				code: 'AGENT_STATIC_PROMPT',
				message: `Is input data required for '${node.name}'? If so, add an expression to the prompt. When following a chat trigger node, use { promptType: 'auto', text: '={{ $json.chatInput }}' }. Or use { promptType: 'define', text: '={{ ... }}' } to add dynamic data like input data.`,
				severity: 'warning',
				nodeName: node.name,
			});
		}

		// Check: No system message
		const options = params.options as Record<string, unknown> | undefined;
		const systemMessage = options?.systemMessage ?? params.systemMessage;
		if (
			!systemMessage ||
			(typeof systemMessage === 'string' && systemMessage.trim().length === 0)
		) {
			issues.push({
				code: 'AGENT_NO_SYSTEM_MESSAGE',
				message: `'${node.name}' has no system message. System-level instructions should be in the system message field.`,
				severity: 'warning',
				nodeName: node.name,
			});
		}

		return issues;
	},
};

View on GitHub (pinned to 5ac6606e81)

Solutions

1. Add options.systemMessage (or top-level systemMessage) with the agent's role/instructions.
2. Ensure the value is a non-empty, non-whitespace string.
3. If intentionally omitted, accept the warning or suppress it via validator configuration.

Example fix

// before
agent({ text: '={{ $json.chatInput }}' })
// after
agent({
  text: '={{ $json.chatInput }}',
  systemMessage: 'You are a helpful assistant that summarizes text.'
})

function hasSystemMessage(p: { systemMessage?: unknown; options?: { systemMessage?: unknown } }): boolean {
  const sm = p.options?.systemMessage ?? p.systemMessage;
  return typeof sm === 'string' && sm.trim().length > 0;
}
if (!hasSystemMessage(agentParams)) {
  // warn: missing system message
}

When it happens

Trigger: Building an agent node and omitting systemMessage entirely, or passing systemMessage: '' / a blank string.

Common situations: Minimal agent setup that only fills the user prompt; migrating a config where the system message key was renamed or dropped.

Related errors

• AGENT_STATIC_PROMPT
• AGENT_STATIC_PROMPT
• Run ${this.runId} is not suspended. Cannot resume.
• Reflector output must be valid JSON
• Reflector output must be a JSON object

AI-assisted analysis of n8n-io/n8n@5ac6606e81 (2026-08-12). Data as JSON: /api/errors/3d283f2ab3c0cab2. Report an issue: GitHub.