AI Agent tool v3 is broken after AI Node updates

[soubhi8]

Bug Description

When an agent is used as tool with main agent and it's connected to a postgres chat memory(same one as the parent agent), the postgres erros with the following
"Missing output data
Expected output #0 from node AI Agent"

This used to work with v2 just fine, but now i want to use the new options of v3.

To Reproduce

Copy the following workflow and run it:
{ "nodes": [ { "parameters": { "httpMethod": "POST", "path": "legal-assistant-prompt", "responseMode": "streaming", "options": { "allowedOrigins": "*", "ignoreBots": false } }, "type": "n8n-nodes-base.webhook", "typeVersion": 2.1, "position": [ -1408, 64 ], "id": "1eb7592a-2a80-41e9-8c32-fe66c9d13fee", "name": "Webhook", "webhookId": "d9896607-daf9-4f14-93a3-fe156415f5ef" }, { "parameters": { "assignments": { "assignments": [ { "id": "a183bd5f-6ba2-49a9-8278-98cf959463c3", "name": "chat_id", "value": "={{ $json.body.chat_id }}", "type": "string" }, { "id": "5d6a1eae-1bef-476d-87fb-92314647be68", "name": "systemPrompt", "value": "={{ $json.body.systemPrompt }}", "type": "string" }, { "id": "96efc04d-ec1e-4a4e-99af-641b6f099c9f", "name": "message_id", "value": "={{ $json.body.message_id}}", "type": "string" }, { "id": "96cba381-c4b8-4556-addb-a93e38e5b402", "name": "sessionId", "value": "={{ $json.body.sessionId}}", "type": "string" }, { "id": "04a43ca8-20ee-4061-af52-a40d2f486c64", "name": "chatInput", "value": "={{ $json.body.chatInput}}", "type": "string" }, { "id": "e7854f6e-8128-4acc-9448-aa06a4b45403", "name": "gitBranch", "value": "develop", "type": "string" }, { "id": "678ba185-1b5a-4694-bc59-5f3c65f9b8c3", "name": "=conversationHistory", "value": "={{ $json.body.conversationHistory?.toJsonString() }}", "type": "string" }, { "id": "772d2658-3444-4fba-b1a9-6df0864a383a", "name": "streaming", "value": "={{ $('Webhook').params.responseMode.toLowerCase() === \"streaming\" }}", "type": "boolean" } ] }, "options": { "ignoreConversionErrors": true, "dotNotation": true } }, "type": "n8n-nodes-base.set", "typeVersion": 3.4, "position": [ -1184, 64 ], "id": "6a969c27-a8a5-4f06-ab58-e6614c6e9b65", "name": "Edit Fields" }, { "parameters": { "toolDescription": "phase 1 - validator AI Agent that given an input, it can validate and check if the input is valid. \nIf input is invalid, it returns validity status and results of the check.\n\nOutput structure:\n{\n \"Valid\": \"true|false\",\n \"Results\": \"Actual Results\"\n}", "text": "={{ /*n8n-auto-generated-fromAI-override*/ $fromAI('Prompt__User_Message_', The user input to be validated goes here, 'string') }}", "options": { "systemMessage": "=return \"{\n \"Valid\": \"true|false\",\n \"Results\": \"valid results\"\n}\"" } }, "type": "@n8n/n8n-nodes-langchain.agentTool", "typeVersion": 2.2, "position": [ -1072, 288 ], "id": "b5c0fac9-59cf-4e4e-a3c2-71952c81967e", "name": "phase 1 - validator Tool" }, { "parameters": { "model": "gpt-4o", "options": { "temperature": 0.7 } }, "type": "@n8n/n8n-nodes-langchain.lmChatAzureOpenAi", "typeVersion": 1, "position": [ -704, 816 ], "id": "b8e6d296-b790-4ae7-acfa-b1b1c263999d", "name": "4o", "credentials": { "azureOpenAiApi": { "id": "eY8uWGOV2iXMDtlJ", "name": "Azure Open AI account" } } }, { "parameters": { "sessionIdType": "customKey", "sessionKey": "={{ $('Edit Fields').item.json.sessionId }}", "contextWindowLength": 15 }, "type": "@n8n/n8n-nodes-langchain.memoryPostgresChat", "typeVersion": 1.3, "position": [ -928, 816 ], "id": "3b45ea38-cb52-4d14-b0be-d3ece32f1136", "name": "Postgres Chat Memory1", "credentials": { "postgres": { "id": "pGmPEnGHHHSlldbM", "name": "Postgres account" } } }, { "parameters": { "toolDescription": "Retrieve a Specific Ruling\n", "url": "=http://www.7timer.info/bin/api.pl?lon=113.17&lat=23.09&product=astro&output=xml", "sendQuery": true, "queryParameters": { "parameters": [ {} ] }, "options": {} }, "type": "n8n-nodes-base.httpRequestTool", "typeVersion": 4.2, "position": [ -544, 560 ], "id": "09f9738a-03e7-44c7-850d-ea7fc06a4a36", "name": "Retrieve a Specific Ruling tool" }, { "parameters": { "toolDescription": "phase 2 - research AI Agent that given an input, it can take it and research further about the topic to find relevant resources like from rechtspraak.nl etc\n\nOutput structure:\n{\n \"Valid\": \"true|false\",\n \"Results\": \"Actual Results\"\n}", "text": "={{ /*n8n-auto-generated-fromAI-override*/ $fromAI('Prompt__User_Message_', ``, 'string') }}", "options": { "systemMessage": "=return \"{\n \"Valid\": \"true|false\",\n \"Results\": \"valid results\"\n}\"", "returnIntermediateSteps": false, "enableStreaming": true } }, "type": "@n8n/n8n-nodes-langchain.agentTool", "typeVersion": 3, "position": [ -704, 304 ], "id": "835ae956-a5a9-4236-9df5-163878615b16", "name": "phase 2 - research tool" }, { "parameters": { "promptType": "define", "text": "=User query:\n{{ $('Edit Fields').item.json.chatInput }}", "options": { "systemMessage": "=Call \"phase 1 - validator Tool\" first then\nCall \"phase 2 - research tool\"", "returnIntermediateSteps": true, "enableStreaming": "={{ $('Edit Fields').item.json.streaming }}" } }, "type": "@n8n/n8n-nodes-langchain.agent", "typeVersion": 3, "position": [ -928, 64 ], "id": "534b1a7d-291d-49d3-976d-139f5d061542", "name": "AI Agent", "alwaysOutputData": false, "onError": "continueErrorOutput" } ], "connections": { "Webhook": { "main": [ [ { "node": "Edit Fields", "type": "main", "index": 0 } ] ] }, "Edit Fields": { "main": [ [ { "node": "AI Agent", "type": "main", "index": 0 } ] ] }, "phase 1 - validator Tool": { "ai_tool": [ [ { "node": "AI Agent", "type": "ai_tool", "index": 0 } ] ] }, "4o": { "ai_languageModel": [ [ { "node": "phase 1 - validator Tool", "type": "ai_languageModel", "index": 0 }, { "node": "phase 2 - research tool", "type": "ai_languageModel", "index": 0 }, { "node": "AI Agent", "type": "ai_languageModel", "index": 0 } ] ] }, "Postgres Chat Memory1": { "ai_memory": [ [ { "node": "phase 1 - validator Tool", "type": "ai_memory", "index": 0 }, { "node": "phase 2 - research tool", "type": "ai_memory", "index": 0 }, { "node": "AI Agent", "type": "ai_memory", "index": 0 } ] ] }, "Retrieve a Specific Ruling tool": { "ai_tool": [ [ { "node": "phase 2 - research tool", "type": "ai_tool", "index": 0 } ] ] }, "phase 2 - research tool": { "ai_tool": [ [ { "node": "AI Agent", "type": "ai_tool", "index": 0 } ] ] }, "AI Agent": { "main": [ [], [] ] } }, "pinData": { "Webhook": [ { "headers": { "host": "", "user-agent": "Python/3.11 aiohttp/3.12.15", "content-length": "1784", "accept": "*/*", "accept-encoding": "gzip, deflate, br", "content-type": "application/json", "x-forwarded-for": "3", "x-forwarded-host": "i", "x-forwarded-port": "443", "x-forwarded-proto": "https", "x-forwarded-server": "dda6093a6dbc", "x-real-ip": "" }, "params": {}, "query": {}, "body": { "systemPrompt": "", "messages": [], "conversationHistory": [], "currentMessage": "Haal naar analogie van Gerards/Vijverberg de essentie uit de uitspraak en pas toe op deze casus: ik heb voor mijn zzp kantoor een huurovereenkomst gesloten met een bedrijf dat deelkantoren verhuurt en ben daar geinstalleerd op de 3e verdieping. Nu 3 maanden later komt dit bedrijf aan met nieuwe voorwaarden. Ze zeggen dat ik op de 4e verdieping had behoren te zitten voor deze prijs en anders een verhoging van de huurprijs moet accepteren. De 4e verdieping is de zolder en die is erg onaangenaam in klimaat. Ik ben van mening dat ik heb getekend voor de 3e en niet voor de 4e verdieping. Als ik had geweten dat ik op de 4e had moeten zitten was ik de overeenkomst niet aangegaan. Wat moet ik doen?", "chat_id": "7ae419f8-4d8a-4028-9c39", "message_id": "55184fd3-43a5-4394-9b52", "sessionId": "4Js-Q7AZJeInpxIdAAJl", "user_id": "45f12f83-72f8-4240-a9ee", "user_email": "blabla@ggagag.com", "user_name": "blablaba", "user_role": "blablaba", "chatInput": "Haal naar analogie van Gerards/Vijverberg de essentie uit de uitspraak en pas toe op deze casus: ik heb voor mijn zzp kantoor een huurovereenkomst gesloten met een bedrijf dat deelkantoren verhuurt en ben daar geinstalleerd op de 3e verdieping. Nu 3 maanden later komt dit bedrijf aan met nieuwe voorwaarden. Ze zeggen dat ik op de 4e verdieping had behoren te zitten voor deze prijs en anders een verhoging van de huurprijs moet accepteren. De 4e verdieping is de zolder en die is erg onaangenaam in klimaat. Ik ben van mening dat ik heb getekend voor de 3e en niet voor de 4e verdieping. Als ik had geweten dat ik op de 4e had moeten zitten was ik de overeenkomst niet aangegaan. Wat moet ik doen?" }, "webhookUrl": "blabla", "executionMode": "production" } ] }, "meta": { "instanceId": "09f8015d3773f4d8d4b2c0e94b51866ac406015ec52275d627e1461850d766d4" } }

Expected behavior

it should work and read/write history without issues

Debug Info

Debug info

core

• n8nVersion: 2.3.5
• platform: docker (self-hosted)
• nodeJsVersion: 22.21.1
• nodeEnv: production
• database: postgres
• executionMode: regular
• concurrency: -1
• license: enterprise (production)
• consumerId: 3603152f-9e4c-474a-9eea-fd26cef40ed5

storage

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

pruning

• enabled: true
• maxAge: 336 hours
• maxCount: 10000 executions

client

• userAgent: mozilla/5.0 (windows nt 10.0; win64; x64) applewebkit/537.36 (khtml, like gecko) chrome/143.0.0.0 safari/537.36 edg/143.0.0.0
• isTouchDevice: false

security

• secureCookie: false

Generated at: 2026-01-15T14:49:30.305Z

Operating System

docker (self-hosted)

n8n Version

2.3.5

Node.js Version

22.21.1

Database

PostgreSQL

Execution mode

main (default)

Hosting

self hosted

[n8n-assistant]

Hey @soubhi8,

Thank you for reaching out! We’ve received your issue and are looking into it. To help us track this internally, we’ve created a Linear ticket with the reference: "GHC-6367".

We’ll keep you updated as we make progress, but if you have any additional details or context to share, feel free to add them here - it’s always helpful!

Thanks for your patience and for bringing this to our attention.

---

For INTERNAL use only: GHC-6367

[esmigol25]

I get that error too, but with Redis.
version of ai agent 3.1 version of n8n 2.3.5