dateTime.format() value will display on output field but when executed returns invalid DateTime

[mkostechuk]

Bug Description

Hello, the previous ticket was closed due to inactivity, but the issue is still there.

DateTime.fromISO() works when editing a node, but doesn't work when full workflow is executed

To Reproduce

1. Paste my simple test workflow

{ "nodes": [ { "parameters": {}, "type": "n8n-nodes-base.manualTrigger", "typeVersion": 1, "position": [ 0, 0 ], "id": "89517ad5-18cc-43a2-8d60-23a6663fb776", "name": "When clicking ‘Execute workflow’" }, { "parameters": { "operation": "get", "dataTableId": { "__rl": true, "value": "RTUmXcXt5SSkmZr6", "mode": "list", "cachedResultName": "test2", "cachedResultUrl": "/projects/Gf5SWUTiJ2Xzg8or/datatables/RTUmXcXt5SSkmZr6" }, "limit": 1 }, "type": "n8n-nodes-base.dataTable", "typeVersion": 1, "position": [ 208, 0 ], "id": "4606fdc5-27a7-4bee-899b-35d3576ec415", "name": "Get row(s)" }, { "parameters": { "assignments": { "assignments": [ { "id": "3f58c229-f02b-4c92-8b10-0c7ecbc2b7bb", "name": "timestamp", "value": "={{ DateTime.fromISO($json.updatedAt).toFormat('dd/MM/yyyy HH:mm:ss') }}", "type": "string" }, { "id": "8b656ed7-bed8-4b48-89a8-b8e4480f774f", "name": "tt", "value": "={{ $json.updatedAt.toDateTime().setZone('Europe/Moscow').toFormat('dd/MM/yyyy HH:mm:ss') }}", "type": "string" } ] }, "includeOtherFields": true, "options": {} }, "type": "n8n-nodes-base.set", "typeVersion": 3.4, "position": [ 416, 0 ], "id": "69cf11a6-ef24-40e8-b73b-fe27b1adc5a4", "name": "Add timestamp" } ], "connections": { "When clicking ‘Execute workflow’": { "main": [ [ { "node": "Get row(s)", "type": "main", "index": 0 } ] ] }, "Get row(s)": { "main": [ [ { "node": "Add timestamp", "type": "main", "index": 0 } ] ] }, "Add timestamp": { "main": [ [] ] } }, "pinData": {}, "meta": { "instanceId": "435a1ecb9e606b9753a6ec0496715a8d59ac35a388e07f71b8ed8bb128b2d349" } }

2. In the get rows node choose any table you have
3. Run the workflow
4. Check the output of the add timestamp node - you'll see "timestamp" field has "Invalid DateTime" output

5. Open editor of the add timestamp node
6. Click "Execute step" button - now you have "timestamp" field with a proper datetime

Expected behavior

I expect DateTime.fromISO() to work properly both in editor and when I execute the full workflow

Debug Info

Debug info

core

• n8nVersion: 2.6.3
• platform: docker (self-hosted)
• nodeJsVersion: 22.22.0
• nodeEnv: production
• database: sqlite
• executionMode: regular
• concurrency: -1
• license: enterprise (production)
• consumerId: bf26dc67-2fd6-475f-9ae6-cdd0af7ee804

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/144.0.0.0 safari/537.36
• isTouchDevice: false

security

• secureCookie: false

Generated at: 2026-02-03T21:01:25.477Z

Operating System

Debian 12

n8n Version

2.6.3

Node.js Version

22.22.0

Database

SQLite (default)

Execution mode

main (default)

Hosting

self hosted

[n8n-assistant]

Hey @mkostechuk,

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-6647".

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.

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For INTERNAL use only: GHC-6647