# EXPERIMENT_RUNNING

- Surface: API
- HTTP status: 409
- Recommended action: `END_RUNNING_RUN_FIRST`
- Details: `{ experimentId: string, runningRunId: string, attemptedOp: string, recommendedAction: RecommendedAction }`

## Cause

The operation is blocked while the Experiment has a live Run. Delete is the common one.

## Fix

End the Run named in `details.runningRunId`, then retry. Ending is deliberate: it stops assignment and seals the measured window rather than discarding it.

## Related

- [RUN_FROZEN](https://splitch.dev/docs/error/RUN_FROZEN)
- [RESOURCE_NOT_EMPTY](https://splitch.dev/docs/error/RESOURCE_NOT_EMPTY)

Source: https://splitch.dev/docs/error/EXPERIMENT_RUNNING