# duplicate_id

**HTTP 409 — Duplicate id**

## When you see it

You supplied an `id` on create and a row with it already exists.

## What to do

Supplying your own id is how you make a create idempotent — so this usually means the write already succeeded. Fetch the row and carry on.

## The response

Every error is [RFC 9457](https://www.rfc-editor.org/rfc/rfc9457) problem+json:

```json
{
  "type": "https://devs.inittasks.com/errors/duplicate_id",
  "title": "Duplicate id",
  "status": 409,
  "detail": "a sentence for a developer; never branch on it",
  "instance": "/todos/8E4F2A1B",
  "request_id": "3f9a1c7e-2b44-4d1e-9c30-5a7e8b2d1f60"
}
```

// Branch on `type`, never on `detail` or on the HTTP status alone — several codes share a status.