Significant-Gravitas/AutoGPT · error · Error

Unexpected n8n API response format

Error message

Unexpected n8n API response format

What it means

Thrown by fetchN8nWorkflow after JSON.parse succeeds but the unwrapped object has no `nodes` array. The code tries several envelope shapes (data.workflow, data itself, template.workflow, template) because the n8n templates API has changed its response shape over time; if none of them yield a workflow with a `nodes` array, the response is considered unparseable. A JSON.parse failure would throw a SyntaxError instead — this error specifically means valid JSON, unexpected shape.

Source

Thrown at autogpt_platform/frontend/src/app/(platform)/library/components/LibraryImportDialog/components/ExternalWorkflowTab/fetchWorkflowFromUrl.ts:82

  const safeId = parseInt(templateId, 10);
  if (!Number.isFinite(safeId) || safeId <= 0) {
    throw new Error("Invalid template ID");
  }
  const res = await fetch(`${N8N_TEMPLATES_API}/${safeId.toString()}`);
  if (!res.ok) throw new Error(`n8n template not found (${res.status})`);

  const contentLength = res.headers.get("content-length");
  if (contentLength && parseInt(contentLength, 10) > MAX_RESPONSE_BYTES) {
    throw new Error("Response too large.");
  }

  const text = await res.text();
  if (text.length > MAX_RESPONSE_BYTES) throw new Error("Response too large.");

  const data = JSON.parse(text);
  const template = data?.workflow ?? data;
  const workflow = template?.workflow ?? template;
  if (!workflow?.nodes) throw new Error("Unexpected n8n API response format");
  if (!workflow.name) workflow.name = template?.name ?? data?.name ?? "";
  return JSON.stringify(workflow);
}

View on GitHub (pinned to 9c8bb5550f)

Solutions

1. Log/inspect the actual JSON returned by the N8N_TEMPLATES_API URL in DevTools to see the new envelope shape.
2. If the shape changed upstream, extend the unwrap chain in fetchN8nWorkflow (add the new path) — this is exactly why the chain exists.
3. Verify the pasted ID is a workflow template, not a collection/credential ID.
4. Retry later / bypass proxies if the payload was rewritten in transit.

Example fix

// before
const template = data?.workflow ?? data;
const workflow = template?.workflow ?? template;

// after (extend envelope chain after confirming new shape)
const template = data?.workflow ?? data?.data ?? data;
const workflow = template?.workflow ?? template;

function hasNodes(workflow: unknown): workflow is { nodes: unknown[]; name?: string } {
  return (
    typeof workflow === "object" && workflow !== null &&
    Array.isArray((workflow as any).nodes)
  );
}

function isN8nWorkflow(data: unknown): data is { nodes: unknown[]; name?: string } {
  return hasNodes(data) || hasNodes((data as any)?.workflow);
}

try {
  const wf = await fetchN8nWorkflow(id);
} catch (error) {
  if (error instanceof Error && error.message === "Unexpected n8n API response format") {
    // upstream shape changed — inspect the raw response and extend the unwrap chain
  }
}

When it happens

Trigger: n8n API returns a redirect/HTML-wrapped payload (proxy interference), an error envelope like {code:..., message:...} with 200 status, or a new API version that nests the workflow differently than the tried paths.

Common situations: n8n ships an API change moving/renaming the workflow field; an intermediary (corporate proxy, CDN) rewriting the response; requesting a non-workflow resource ID that returns metadata-only JSON with 200.

Related errors

• n8n template not found (${res.status})
• Response too large.
• Authentication failed — please sign in again.
• Failed to fetch session (status: ${response.status})
• Invalid form

AI-assisted analysis of Significant-Gravitas/AutoGPT@9c8bb5550f (2026-08-14). Data as JSON: /api/errors/5cc1726848472124. Report an issue: GitHub.