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

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# Flow run events

> Events emitted during flow run state transitions and heartbeats.

Flow run events track the lifecycle of every flow run, from scheduling through
completion. They are emitted on every state transition and, optionally, as
periodic heartbeats during execution.

## `prefect.flow-run.{state}`

Emitted each time a flow run transitions to a new state. The `{state}` suffix is
the state name (for example, `prefect.flow-run.Running` or
`prefect.flow-run.Completed`).

### State variants

| State name                | State type | Description                                           |
| ------------------------- | ---------- | ----------------------------------------------------- |
| `Scheduled`               | SCHEDULED  | Run is scheduled for future execution                 |
| `Late`                    | SCHEDULED  | Scheduled run was not started on time                 |
| `AwaitingConcurrencySlot` | SCHEDULED  | Waiting for a concurrency slot                        |
| `AwaitingRetry`           | SCHEDULED  | Waiting before a retry attempt                        |
| `Pending`                 | PENDING    | Run is ready to execute                               |
| `Running`                 | RUNNING    | Run is actively executing                             |
| `Retrying`                | RUNNING    | Run is retrying after a failure                       |
| `Completed`               | COMPLETED  | Run finished successfully                             |
| `Failed`                  | FAILED     | Run finished with an error                            |
| `Crashed`                 | CRASHED    | Run terminated unexpectedly (infrastructure failure)  |
| `Cancelled`               | CANCELLED  | Run was cancelled                                     |
| `Cancelling`              | CANCELLING | Cancellation was requested but not yet confirmed      |
| `Paused`                  | PAUSED     | Run is paused, waiting for input or manual resumption |
| `Suspended`               | PAUSED     | Run is suspended and its infrastructure may be freed  |

### Resource

| Label                     | Description                                                                    |
| ------------------------- | ------------------------------------------------------------------------------ |
| `prefect.resource.id`     | `prefect.flow-run.{uuid}`                                                      |
| `prefect.resource.name`   | Flow run name (for example, `crimson-fox`)                                     |
| `prefect.run-count`       | Number of times this run has been attempted                                    |
| `prefect.state-message`   | Message associated with the state transition (truncated to 100,000 characters) |
| `prefect.state-name`      | State name (for example, `Running`)                                            |
| `prefect.state-timestamp` | ISO 8601 timestamp of the state transition                                     |
| `prefect.state-type`      | State type enum value (for example, `RUNNING`, `COMPLETED`)                    |

### Related resources

| Resource ID pattern                                        | Role         | When present                                                           |
| ---------------------------------------------------------- | ------------ | ---------------------------------------------------------------------- |
| `prefect.flow.{uuid}`                                      | `flow`       | Always                                                                 |
| `prefect.deployment.{uuid}`                                | `deployment` | When triggered by a deployment                                         |
| `prefect.work-queue.{uuid}`                                | `work-queue` | When a work queue is assigned                                          |
| `prefect.work-pool.{uuid}`                                 | `work-pool`  | When a work pool is assigned (includes `prefect.work-pool.type` label) |
| `prefect.task-run.{uuid}`                                  | `task-run`   | When the flow run is a subflow called from a task                      |
| `prefect.tag.{tag}`                                        | `tag`        | One entry per tag on the flow run or its flow/deployment               |
| `prefect.deployment.{uuid}` or `prefect.automation.{uuid}` | `creator`    | Provenance: which deployment or automation created this run            |

### Payload

| Field             | Type           | Description                                                                 |
| ----------------- | -------------- | --------------------------------------------------------------------------- |
| `intended.from`   | string or null | State type of the initial state (null for the first transition)             |
| `intended.to`     | string         | State type of the validated (new) state                                     |
| `initial_state`   | object or null | Previous state: `type`, `name`, `message`, and `pause_reschedule` if paused |
| `validated_state` | object         | New state: `type`, `name`, `message`, and `pause_reschedule` if paused      |

<Expandable title="Example: flow run transitions to Running">
  ```json  theme={null}
  {
    "occurred": "2026-03-31T18:30:00.000000Z",
    "event": "prefect.flow-run.Running",
    "resource": {
      "prefect.resource.id": "prefect.flow-run.e3755d32-cec5-42ca-9bcd-af236e308ba6",
      "prefect.resource.name": "crimson-fox",
      "prefect.run-count": "1",
      "prefect.state-message": "",
      "prefect.state-name": "Running",
      "prefect.state-timestamp": "2026-03-31T18:30:00.000000Z",
      "prefect.state-type": "RUNNING"
    },
    "related": [
      {
        "prefect.resource.id": "prefect.flow.a1b2c3d4-e5f6-7890-abcd-ef1234567890",
        "prefect.resource.name": "my-etl-flow",
        "prefect.resource.role": "flow"
      },
      {
        "prefect.resource.id": "prefect.deployment.b2c3d4e5-f6a7-8901-bcde-f12345678901",
        "prefect.resource.name": "my-etl-flow/production",
        "prefect.resource.role": "deployment"
      },
      {
        "prefect.resource.id": "prefect.work-pool.c3d4e5f6-a7b8-9012-cdef-123456789012",
        "prefect.resource.name": "my-k8s-pool",
        "prefect.work-pool.type": "kubernetes",
        "prefect.resource.role": "work-pool"
      },
      {
        "prefect.resource.id": "prefect.tag.production",
        "prefect.resource.role": "tag"
      }
    ],
    "payload": {
      "intended": {
        "from": "PENDING",
        "to": "RUNNING"
      },
      "initial_state": {
        "type": "PENDING",
        "name": "Pending"
      },
      "validated_state": {
        "type": "RUNNING",
        "name": "Running"
      }
    },
    "id": "f6a7b890-1234-5678-9012-abcdef345678",
    "follows": "d4e5f6a7-b890-1234-5678-9012abcdef34"
  }
  ```
</Expandable>

## `prefect.flow-run.heartbeat`

Emitted periodically during flow run execution when heartbeat frequency is configured.
Used for liveness detection, particularly with
[zombie flow detection](/v3/advanced/detect-zombie-flows).

### Resource

| Label                   | Description               |
| ----------------------- | ------------------------- |
| `prefect.resource.id`   | `prefect.flow-run.{uuid}` |
| `prefect.resource.name` | Flow run name             |
| `prefect.version`       | Prefect SDK version       |

### Related resources

| Resource ID pattern         | Role         | When present                   |
| --------------------------- | ------------ | ------------------------------ |
| `prefect.flow.{uuid}`       | `flow`       | Always                         |
| `prefect.deployment.{uuid}` | `deployment` | When triggered by a deployment |
| `prefect.tag.{tag}`         | `tag`        | One entry per tag              |

### Payload

This event has no payload.


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