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

# Errors

> One error shape, and what each status code means here.

Every failure answers with the same body:

```json theme={null}
{ "error": "Unknown placeholder {source} in destinationUrl" }
```

The HTTP status carries the category; `error` is English prose for a human. Branch on the status, not on the wording.

## Status codes

| Status | What it means here                                                                                                                                                                                |
| ------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `400`  | The request is wrong. Ad copy that breaks a rule, an unknown `{placeholder}`, a strike-out list that leaves no channels, an amount that is not a decimal. The message names the specific problem. |
| `401`  | Missing, unknown, disabled or expired API key. See [Authentication](/api/authentication).                                                                                                         |
| `402`  | **Not enough money.** Your balance does not cover what you asked for, or an API key's credit limit is exhausted. [Top up](/billing/deposits) or raise the key's limit.                            |
| `403`  | Authenticated, but not allowed to touch this object.                                                                                                                                              |
| `404`  | No such object — or it belongs to someone else.                                                                                                                                                   |
| `409`  | The object is not in a state that allows this. Approving a placement that is not awaiting approval, for instance.                                                                                 |
| `500`  | Our fault. Safe to retry with the same `idempotencyKey`.                                                                                                                                          |
| `502`  | An upstream service Aflux depends on failed — the AI provider, the channel index, the payment provider. Transient; retry.                                                                         |

## Validation errors are not errors

Ad-copy validation is the exception worth knowing about. `POST /api/v1/campaigns/ad-copy/validate` answers **`200`** with `valid: false` and a list of problems — the text being wrong is the expected outcome of asking, not a failed request.

Campaign creation, by contrast, refuses the same text with a `400` whose message lists every problem and the span of markup each occupies. See [Ad copy](/guides/ad-copy).

## Retrying safely

Only campaign creation is idempotent, through `idempotencyKey`. Reuse the same UUID for a retry of the same intent; anything else creates a second campaign and a second charge.

Everything else is either a read, or an action guarded by the object's own state — approving an already-approved placement is a `409`, not a double charge.