> ## Documentation Index
> Fetch the complete documentation index at: https://mixpanel-edb78807-copilot-tof-446-create-per-error-troubles.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# 401 Unauthorized

> Why Mixpanel's ingestion API returns a 401, which credentials each endpoint accepts, and how regional data residency affects authentication

A 401 means Mixpanel could not authenticate the request. The credentials were missing, malformed, or not valid for the project you addressed.

## What the Response Looks Like

```json theme={"system"}
{
  "code": 401,
  "error": "Invalid credentials",
  "status": "Unauthorized"
}
```

## Which Credentials Each Endpoint Accepts

| Endpoint                       | Accepted credentials                                                                                                                                                                                 |
| ------------------------------ | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `/import`                      | An Owner or Admin [Service Account](/reference/service-accounts) with `project_id`, a [Project Token](/reference/project-token) as the basic-auth username with an empty password, or an OAuth token |
| `/track`, `/engage`, `/groups` | A project token sent in the payload                                                                                                                                                                  |

<Note>
  A bad project token on `/track` does not produce a 401. The endpoint returns `200` with a body of `1`, which confirms the payload was well-formed but says nothing about whether the token is valid. Add `?verbose=1` to get a JSON response instead, and check your project's live view to confirm events are arriving.
</Note>

## Common Causes

### Service Account Lacks the Required Role

`/import` requires an Owner or Admin Service Account. A Service Account with a lower role authenticates but is not permitted to import.

### Missing `project_id`

When authenticating with a Service Account, `project_id` is required. Without it, Mixpanel cannot tell which project the credentials apply to.

### Wrong Regional Endpoint

Projects with EU or India data residency use different hosts. Sending correct credentials to the wrong host fails, because the project does not exist there.

| Residency | Host                  |
| --------- | --------------------- |
| US        | `api.mixpanel.com`    |
| EU        | `api-eu.mixpanel.com` |
| India     | `api-in.mixpanel.com` |

See [EU Residency](/docs/privacy/eu-residency) and [India Residency](/docs/privacy/in-residency).

### Malformed Basic Auth Header

Basic auth expects a base64-encoded `username:password` pair. A common mistake is encoding only the username, or omitting the colon when the password is empty.

## How to Fix It

**Confirm the credential type** matches what the endpoint accepts, using the table above.

**Check the Service Account's role** at Project Settings → Service Accounts. It must be Owner or Admin for `/import`.

**Verify your project's residency** and send to the matching host.

## Related

* [Service Accounts](/reference/service-accounts)
* [403 Forbidden](/troubleshooting/errors/403-forbidden)
* [Find your project token](/docs/orgs-and-projects/managing-projects#find-your-project-tokens)