# n8n OpenAI Node Errors: 401, Empty Model List, Raw Braces > Fix n8n OpenAI node problems: "401 Authorization failed", a Model list that won't load, {{ }} sent as plain text, long answers and costs per item. Source: https://learn.ynteractive.com/content/blog/n8n-openai-node-errors · Updated 2026-10-20 · Free from Stepthrough (https://learn.ynteractive.com) Quick answer "401 Authorization failed" in the n8n [OpenAI](https://learn.ynteractive.com/content/glossary/openai) node means the [API key](https://learn.ynteractive.com/content/glossary/api-key) in the chosen credential doesn't work: it's revoked, mistyped, or belongs to an account with no billing set up. n8n often pre-fills a credential for you, so click the **Credential** box and pick the one with your working key; the **Model** list loads once it does. The free [n8n weekly client status email](https://learn.ynteractive.com/content/weekly-client-status-email-google-sheets-ai-n8n) lesson ran into exactly this in a real test. Last updated October 20, 2026 [Take the free module →](https://learn.ynteractive.com/courses/n8n-jump-start/8)Module 8 of the free [n8n Jump Start](https://learn.ynteractive.com/courses/n8n-jump-start) course, about 14 minutes. No account needed. By [Robert Breen](https://learn.ynteractive.com/content/about) · Published October 20, 2026 · Updated October 20, 2026 · 3 min read n8n · OpenAI · Troubleshooting ## "401 Authorization failed" The key was rejected. In the lesson's test, n8n had pre-filled an account with a dead key, and the model list failed with 401 Authorization failed. Fix: 1. Click the **Credential** box and pick the credential you know works. 2. No working credential? Make a key on the [OpenAI API](https://learn.ynteractive.com/content/glossary/openai-api) Keys page, add funds under Billing, and paste the key into a new credential. 3. Click the **Model** box. If the list loads, the key works. An [API key](https://learn.ynteractive.com/content/glossary/api-key) is a secret; never paste it into a prompt or a sheet. ## The Model list is empty or spinning The list loads from OpenAI using the credential, so an empty list is almost always the same key problem as a 401. Fix the credential first. If the key is new, wait a minute and try again. ## The `{{ }}` parts reach OpenAI as plain text The Prompt field is still in Fixed mode, so `{{ $json.Client }}` is sent as those exact characters. Fix: hover over the **Prompt** box and click **Expression**. The braces turn green and a **Result** line shows the first row's real values. In the lesson's test, skipping this sent the braces to OpenAI as plain text. The same goes for Gmail's Subject, Message and To Email fields. [n8n Expressions for Beginners](https://learn.ynteractive.com/content/blog/n8n-expressions-for-beginners) explains Fixed vs Expression. ## "429" or "exceeded your current quota" A 429 can be a rate limit or an account with no credit. If the message says quota, add credit; slowing down won't help. Fix OpenAI 429 in n8n covers both. ## The answer is far too long The prompt doesn't set a length. In the [Google Sheets lesson](https://learn.ynteractive.com/content/n8n-google-sheets-read-append-update), the template's system message said only "write a description" and the model wrote whole paragraphs. Changing it to "Take in the topic and write a one-sentence description" fixed it. The client status lesson asks for "under 90 words". ## Costs add up faster than expected The AI node runs once per item. In the Google Sheets lesson the agent shows **9 items** and makes 9 OpenAI calls. That's cheap for nine rows, but it adds up on a long sheet. Filter out rows that don't need AI before the node, and use a small model like gpt-4o-mini or GPT-4.1-MINI for short tasks. ## The AI makes things up Tell it not to and give it only the facts. The client status prompt ends with "Do not invent facts", and the workflow saves Gmail drafts rather than sending, so a person reads each one first. The [meeting notes lesson](https://learn.ynteractive.com/content/meeting-notes-to-action-items-google-sheets-ai-n8n) adds the habit: read the AI tasks before you rely on them. ## Try it free, step by step **n8n: Weekly Client Status Emails from a Google Sheet, Written by AI**. Build an n8n workflow that wakes up every Monday, reads your client tracker in Google Sheets, has AI write a friendly update for each client and saves it as a Gmail draft. You do every step yourself in a practice copy of n8n, it checks your work as you go, and “Do it for me” finishes any step you get stuck on. Free, and nothing touches your real accounts. [Start the free lesson](https://learn.ynteractive.com/modules/n8n-client-status-email) [Or read the full step-by-step guide](https://learn.ynteractive.com/content/weekly-client-status-email-google-sheets-ai-n8n) ## Where is the answer in the output? For **Message a model**, the text is at `{{ $json.output[0].content[0].text }}`. If a later node shows nothing, check you mapped that path, not `$json.text` or `$json.message`. ## Key takeaways - 401 Authorization failed means the credential's key doesn't work; pick or create a working one. - An empty Model list is a credential problem, not a model problem. - Switch prompt fields to Expression, or the braces are sent as text. - AI nodes run once per item: limit length, filter rows and pick a small model. ## Frequently asked questions **Why does n8n say 401 Authorization failed for OpenAI?** The API key in the selected credential is invalid, revoked or tied to an account without billing. Select or create a credential with a working key. **Do I need ChatGPT Plus to use OpenAI in n8n?** No. n8n uses the OpenAI API, which is billed separately and pay-as-you-go. Add funds under Billing on the OpenAI platform. **Why does my prompt show {{ $json.Client }} in the AI's answer?** The field was left in Fixed mode. Switch it to Expression so n8n fills in the value before sending. **Which course is this from?** [n8n Jump Start](https://learn.ynteractive.com/courses/n8n-jump-start) and [AI for Consulting & Agencies](https://learn.ynteractive.com/courses/ai-for-consulting-and-agencies). ## Free lessons in this post - [n8n: Weekly Client Status Emails from a Google Sheet, Written by AI](https://learn.ynteractive.com/content/weekly-client-status-email-google-sheets-ai-n8n): Build an n8n workflow that wakes up every Monday, reads your client tracker in Google Sheets, has AI write a friendly update for each client and saves it as a Gmail… - [n8n: Turn Meeting Notes into Action Items in a Google Sheet](https://learn.ynteractive.com/content/meeting-notes-to-action-items-google-sheets-ai-n8n): Build an n8n workflow that reads your meeting notes from a sheet, has AI pull out who agreed to do what by when, and adds one row per task to an Action Items sheet. - [n8n: Read, Add and Update Google Sheets Rows with an AI Step](https://learn.ynteractive.com/content/n8n-google-sheets-read-append-update): Learn n8n's three core Google Sheets moves on a made-up request list: read the rows, add a new one without duplicates, then let an AI step write a description and… ## Watch it in a free lesson: AI Receipt Extractor: Receipts to Google Sheets with n8n ### AI Receipt Extractor: video walkthrough Full walkthrough · 5:35 · with captions Drop a photo of a receipt into an n8n chat. An AI agent reads it, pulls out the date, vendor and amount, picks a category, and adds a row to Google Sheets. The whole lesson narrated step by step, recorded in Stepthrough’s simulated practice environment. [Watch it with chapters and the full transcript](https://learn.ynteractive.com/content/ai-receipt-extractor-n8n-google-sheets#watch) From the free lesson [AI Receipt Extractor: Receipts to Google Sheets with n8n](https://learn.ynteractive.com/content/ai-receipt-extractor-n8n-google-sheets) ## Related terms Plain-English definitions, each with an example from a free lesson. [OpenAI](https://learn.ynteractive.com/content/glossary/openai) · [API key](https://learn.ynteractive.com/content/glossary/api-key) · [OpenAI API](https://learn.ynteractive.com/content/glossary/openai-api) · [Coda](https://learn.ynteractive.com/content/glossary/coda) · [Customer health score](https://learn.ynteractive.com/content/glossary/customer-health-score) · [JSON array](https://learn.ynteractive.com/content/glossary/json-array) · [Manual trigger](https://learn.ynteractive.com/content/glossary/manual-trigger) · [n8n data store node (Data table)](https://learn.ynteractive.com/content/glossary/data-store-node) [The full AI glossary](https://learn.ynteractive.com/content/glossary) ## Related prompts - [Client onboarding questionnaire prompt](https://learn.ynteractive.com/content/prompts/client-onboarding-questionnaire-prompt): Copy this ChatGPT prompt to write a client onboarding questionnaire: only what you need before kickoff, grouped, short, nothing… - [Weekly status email to manager prompt](https://learn.ynteractive.com/content/prompts/weekly-status-email-to-manager-prompt): A ChatGPT prompt for a weekly status email to your manager: wins with numbers, what slipped and why, what you need from them… [All free prompt templates](https://learn.ynteractive.com/content/prompts) ## Keep reading - [n8n Google Sheets Errors: Sheet Not Found and 5 More](https://learn.ynteractive.com/content/blog/n8n-google-sheets-errors): Fix n8n Google Sheets errors: "Sheet with ID gid=0 not found", "At least one value has to be added under Values to Send", permissions and columns. - [n8n Google Sheets Node Cheat Sheet: Get, Append, Update](https://learn.ynteractive.com/content/blog/n8n-google-sheets-node-cheat-sheet): Every n8n Google Sheets operation on one page: Get row(s), Append row, Append or update row, Update row, Column to match on and Map Automatically. - [n8n Workflow Ideas for Marketing Teams: 10 to Build](https://learn.ynteractive.com/content/blog/n8n-workflow-ideas-for-marketing): Ten n8n and Make workflow ideas for marketers: content requests with AI drafts, weekly client updates, lead magnets, social posts and routing. 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