# Conflict

The request clashes with the current state: it already exists, or it is not possible yet. 409.

Pattern: `conflict.*` (this page) · Raised with: [`fail()`](https://www.prongs.dev/docs/profiles/errors.md) · Intents: [2](#intents) · Statuses: `409`

## Intents

| Intent | Status | Use it for |
|---|---|---|
| [`conflict.duplicate`](https://www.prongs.dev/docs/intents/conflict/duplicate.md) | `409` | It would create something that exists: a taken handle or email, a second follow |
| [`conflict.state`](https://www.prongs.dev/docs/intents/conflict/state.md) | `409` | Not possible right now: create your page first, already published |

## Raising one

Name what went wrong. The intent sets the status, the message the caller sees, and any log it writes.

```ts
// It would create something that exists: a taken handle or email, a second follow
return fail('conflict.duplicate', 'That handle is already taken.');

// Not possible right now: create your page first, already published
return fail('conflict.state', 'Create your page first.');
```

The caller gets (conflict.duplicate)

```bash
HTTP 409

{
  "ok": false,
  "error": "That handle is already taken.",
  "code": "conflict.duplicate"
}
```

## Is it a conflict error?

Find the row that describes your case, and use the domain on the right.

| If the problem is | Use |
|---|---|
| The caller’s request was wrong: unreadable, incomplete, or a value that breaks a rule. 400 or 422. | [`request.*`](https://www.prongs.dev/docs/intents/request.md) |
| No valid credentials: nobody signed in, an expired session, a bad token or secret. 401. | [`auth.*`](https://www.prongs.dev/docs/intents/auth.md) |
| Valid credentials, but not allowed to do this. 403. | [`permission.*`](https://www.prongs.dev/docs/intents/permission.md) |
| The thing asked for is not there, as far as the caller may know. 404. | [`record.*`](https://www.prongs.dev/docs/intents/record.md) |
| The request clashes with the current state: it already exists, or it is not possible yet. 409. | `conflict.*` (this page) |
| Too many requests, or an allowance used up. 429. | [`limit.*`](https://www.prongs.dev/docs/intents/limit.md) |
| Our fault or a dependency’s. The caller sees a generic message; the details are logged. 5xx. | [`failure.*`](https://www.prongs.dev/docs/intents/failure.md) |

## For registry authors

**Starter intents.** These are the intents `prongs add errors` puts in your registry, raised with [`fail()`](https://www.prongs.dev/docs/profiles/errors.md). Change the messages to suit your app, and the statuses through the [`status.*`](https://www.prongs.dev/docs/intents/errors.md#status) intents they are built from.