# Simulation already running

You're trying to run a simulation while another run for this simulation is pending.

---

## Example

```json
{
  "error": {
    "type": "request_error",
    "code": "notification_simulation_already_running_conflict",
    "detail": "Simulations cannot be run while another run is pending.",
    "documentation_url": "https://developer.paddle.com/errors/notifications/notification_simulation_already_running_conflict"
  },
  "meta": {
    "request_id": "00000000-0000-0000-0000-000000000000"
  }
}
```

## Details

| Attribute | Value |
| --- | --- |
| Status code | 409 |
| Error code | `notification_simulation_already_running_conflict` |
| Error message | Simulations cannot be run while another run is pending. |

## Common causes

- Only one simulation run for a simulation can be running at one time. You're trying to run a simulation while another run is pending.

## Common solutions

- Wait for the current simulation run to complete, then try your run again.