> ## Documentation Index
> Fetch the complete documentation index at: https://docs.emailfinderverifier.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Errors

> Status codes and error codes the API returns.

Errors come back as JSON with a human-readable `error` and a stable `code` you can branch on:

```json theme={null}
{ "detail": { "error": "Domain is required", "code": "MISSING_DOMAIN" } }
```

| Status | Code | What it means | What to do |
| - | - | - | - |
| `400` | `INVALID_EMAIL` | The `email` value isn't an email address. | Fix the input. |
| `400` | `MISSING_DOMAIN` | `domain` is missing or empty. | Send a domain like `acme.com`. |
| `400` | `MISSING_FIRST_NAME`, `MISSING_LAST_NAME` | A name field on `/find` is empty. | Send both names. |
| `400` | `INVALID_REQUEST` | A required parameter is missing or has the wrong type. | Check the parameter names in the [API reference](https://docs.emailfinderverifier.com/api-reference/verify/verify-an-email.md). |
| `401` | `INVALID_API_KEY` | The `X-API-Key` header is missing or the key is wrong or revoked. | Check the key in the dashboard. |
| `402` | `OUT_OF_CREDITS` | Your balance is used up. | Check [`/api/v1/credits`](https://docs.emailfinderverifier.com/api-reference/account/check-your-balance). |
| `403` | `ACCOUNT_NOT_FOUND`, `ACCOUNT_NOT_ACTIVE` | The account behind the key can't use the API right now. | Sign in to the dashboard to see why. |
| `429` | `RATE_LIMIT_EXCEEDED` | You sent more requests than your [limits](https://docs.emailfinderverifier.com/limits.md) allow. | Wait and retry with backoff. |
| `429` | `CONCURRENT_LIMIT_EXCEEDED` | Too many requests are running at the same time. | Lower your concurrency. |
| `500` | | Something failed on our side. | Retry. If it keeps happening, tell us. |
| `503` | | The service is briefly unavailable. | Retry after a few seconds. |

## Retrying

Retry `429`, `500` and `503` with exponential backoff (for example 1s, 2s, 4s, up to a minute). Don't retry `400`, `401`, `402` or `403` without changing something first.


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