---
title: "Migrate Running Experiments"
method: POST
path: "/api/experiments/migrate-running"
tags: ["Experiments"]
---

# Migrate Running Experiments

`POST /api/experiments/migrate-running`

Register the currently-running legacy experiments as ``running`` rows
(synchronous, commits immediately) and kick off the historical
``ab_assignment`` backfill from ``ab_arms`` in the BACKGROUND — the backfill
is a heavy bulk INSERT that would blow the HTTP timeout, so it runs unbound
by the request. Both halves are idempotent; poll ``GET /sync-check`` for
backfill progress (``checked`` grows as it lands).

## Headers

- `x-admin-token` string, nullable

## Response `200`

Successful Response

- unknown

## Other responses

- `422` — Validation Error

---

[API](https://skmtc.dev/explee/apis/explee-api.md) · [All operations](https://skmtc.dev/explee/apis/explee-api/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/explee/explee-api/revisions/f169bc6e9447/schema)