---
title: "A cancelled date in a season was replaced, and one holder was moved to the replacement."
method: POST
path: "pass_series.leg_substituted"
tags: ["pass_series.* events"]
---

# A cancelled date in a season was replaced, and one holder was moved to the replacement.

`POST pass_series.leg_substituted` (webhook)

### When this fires

A creator cancelled a window that a season ticket points at, a replacement was available, and one holder was moved onto it. Their season carries on at the same length.

Fires **once per holder**, not once per cancellation. Each holder is resettled individually because the outcomes differ: someone already holding the replacement date skips past it to the next one they do not have, and someone with no replacement available is dropped instead.

### Caveats

- **`was_queued` is the field worth branching on.** A holder who was queued stays queued for the new date and is told there is nothing to do. One who was not usually gets their invite link attached, except a holder who had already been admitted to the cancelled window: they also report `was_queued: false`, but their access is revoked and they are told a fresh link arrives when the new window opens, so no link is attached. `was_queued: false` therefore covers two different situations; if you need to tell them apart, check whether the holder currently has access. If you send your own message alongside ours, match that split or you will ask half your audience to do something they have already done.
- The holder is **never** moved onto a date they already hold. The next one they do not have is chosen instead, so `to_window_id` can be further out than the immediate next window.
- Three groups are skipped entirely and produce no event: holders who are **paused**, **past due**, or who **cancelled their own series**. They still paid for a date that is not happening. Check subscriptions on that plan before reaching for a refund list.
- `plan_id` is the **source** plan. To identify the series, read `subscription_id`.

### Related events

- `pass.holder_moved`: the same resettlement on an ordinary single-window pass rather than a series.
- `pass_series.leg_dropped`: what happens when no replacement exists.
- `pass.window_cancelled`: fires once, last, carrying both tallies.

## Headers

- `SB-Signature` string, required
- `SB-Event-Id` string, required
- `SB-Event-Name` string, required
- `Content-Type` string, required
- `User-Agent` string, required

## Payload

- object: The envelope every event is delivered in.
  - `id` string, required: A ULID unique to the event, prefixed `evt_`. Every retry carries the same id, so it is the key to deduplicate on.
  - `type` 'pass_series.leg_substituted', required: The event name, always `pass_series.leg_substituted` here.
  - `created_at` string, date-time, required: When the event was emitted, server time, ISO 8601.
  - `api_version` string, required: The contract version of the payload shape, `2026-05-01` today. A breaking change to a shape ships under a new version.
  - `project_id` string, uuid, nullable, required: The project the event belongs to; null for team-scoped and billing events.
  - `data` object, required: The event-specific payload. Keys that do not apply to a given emission are omitted rather than sent as null, so check for presence.
    - `subscription_id` string, uuid, required: The season ticket that was resettled.
    - `subscriber_id` string, uuid, required: The holder who moved.
    - `plan_id` string, uuid, required: The plan the **windows** belong to: the source pass plan, not the series.
    - `from_window_id` string, uuid, required: The cancelled window.
    - `from_starts_at` string, date-time, required: Cancelled window start, **always UTC**.
    - `from_ends_at` string, date-time, required: Cancelled window end, always UTC.
    - `to_window_id` string, uuid, required: The replacement window they now hold.
    - `to_starts_at` string, date-time, required: Replacement start, always UTC.
    - `to_ends_at` string, date-time, required: Replacement end, always UTC.
    - `was_queued` boolean, required: Whether they still had a **pending** join request on the cancelled date: tapped their invite link and not yet admitted. Someone already admitted to the cancelled window reports `false` even though they tapped, because admission consumes the request.

## Acknowledgement `2XX`

Your endpoint acknowledged the delivery. Any 2xx status within 30 seconds marks it delivered; the response body is ignored.

## Other responses

- `default`: Any other status, a connection failure, or no answer within 30 seconds counts as a failed attempt. The delivery is retried 8 times, after 10 seconds, 30 seconds, 2 minutes, 10 minutes, 1 hour, 6 hours, 1 day, 3 days; the last failure dead-letters it, and it can be retried from the dashboard or `POST /v1/webhook-deliveries/{delivery}/retry`. After 20 consecutive failures the endpoint is paused until it is resumed.

---

[API](https://skmtc.dev/memberpass/apis/subscriby-rest-api.md) · [All operations](https://skmtc.dev/memberpass/apis/subscriby-rest-api/llms.txt) · [OpenAPI document](https://skmtc.dev/memberpass/apis/subscriby-rest-api/revisions/59c4df91d764?raw)