# Session Already Processed

Indicates the checkout has already been processed. Check the transaction status by calling our `get transaction` endpoint.

## Common Causes

- The checkout has already completed successfully.
- A duplicate processing request is sent for the same checkout.
- A retry occurs after the transaction has already been captured.

```json
{
  "type": "https://developer.sumup.com/problem/session-already-processed",
  "title": "Conflict",
  "status": 409,
  "detail": "The checkout session ae98b9cc-2287-4621-afa1-d36ae2ea219d is already processed",
  "instance": "1bfe72b34387"
}
```