Bug Description

I have a very simple workflow that receives a *chat message and calls OpenAI API through Basic LLM Chain with Structured Output Parser attached.

The workflow is always failing on the output validation.

One of the debugging steps I tried was to re-create it as a new workflow. And that one works! The new workflow for some reason used some older nodes and that fixed the issue. So the latest versions are broken.

Failing workflow:
Chat Trigger node version 1.4 (Latest)
Basic LLM Chain node version 1.7 (Latest)
OpenAI Chat Model node version 1.3 (Latest)
Structured Output Parser node version 1.3 (Latest)

Working workflow:
Chat Trigger node version 1.3
Basic LLM Chain node version 1.7 (Latest)
OpenAI Chat Model node version 1.2
Structured Output Parser node version 1.3 (Latest)

To Reproduce

1. Import these two workflows
2. Add your API credentials
3. Send "hi" to chat.

failing.json
working.json

The first one fails, the second one passes

Expected behavior

Both workflows should be passing

Debug Info

Debug info

core

• n8nVersion: 1.120.4
• platform: docker (cloud)
• nodeJsVersion: 22.21.0
• nodeEnv: production
• database: sqlite
• executionMode: regular
• concurrency: 20
• license: community
• consumerId: 00000000-0000-0000-0000-000000000000

storage

• success: all
• error: all
• progress: false
• manual: true
• binaryMode: filesystem

pruning

• enabled: true
• maxAge: 720 hours
• maxCount: 25000 executions

client

• userAgent: mozilla/5.0 (macintosh; intel mac os x 10_15_7) applewebkit/537.36 (khtml, like gecko) chrome/142.0.0.0 safari/537.36
• isTouchDevice: false

Generated at: 2025-11-22T19:55:32.533Z

Operating System

docker (cloud)

n8n Version

1.120.4

Node.js Version

22.21.0

Database

SQLite (default)

Execution mode

main (default)

Hosting

n8n cloud