---
title: "401 — key rejected"
url: https://lumean.app/en/developers/docs/errors/401
locale: en
description: "The request was rejected before any business logic ran: no action was performed and nothing was charged. The body is the same on every endpoint: `{\"success\": false, \"message\": \"API key is missing. Provide it in the X-API-KEY header.\", \"data\": null}`. The public API does not accept anonymous requests anywhere."
generated: 2026-10-17
---

# 401 — key rejected

- HTTP: `401`

- `Retry-After` header: no

## What happened

The request was rejected before any business logic ran: no action was performed and nothing was charged. The body is the same on every endpoint: `{"success": false, "message": "API key is missing. Provide it in the X-API-KEY header.", "data": null}`. The public API does not accept anonymous requests anywhere.

## Why

The `X-API-KEY` header was not sent, was sent with a typo in its name, or its value was truncated when copied — or the key is unknown, deactivated, or expired. The Bearer token of the web dashboard does not work here: the public API authenticates only with an API key, and vice versa — an API key does not open dashboard endpoints.

## What to do

Make sure the header is named exactly `X-API-KEY` (not `Authorization`, not `Api-Key`) and the value is sent in full. If the key is correct, open the developer section and check that the key is active and has not expired. Retrying is pointless: a 401 is deterministic, and a retry with the same key gets the same response.

## Next request

`GET /user` is the cheapest way to check a key. A 200 means the key is alive; a 403 also means authentication succeeded (the key simply lacks the `profile.read` scope) — and only a repeated 401 confirms that the problem is the key itself.

## Related

- [Guide: API keys, scopes, and headers](https://lumean.app/en/developers/docs/guide/authentication)
- [GET /user](https://lumean.app/en/developers/docs/api/get-user)
- [My API keys](https://lumean.app/en/developers)
- [403 — insufficient permissions](https://lumean.app/en/developers/docs/errors/403)

---

- This page in the browser: https://lumean.app/en/developers/docs/errors/401
- Full machine-readable reference: https://api.lumean.app/docs/llm.md