Use your event sources and audiences on each seller account

How it works

You define an event source (a stream of conversions you send with log_event) or an audience (a list of people you sync with save_audience) once, for the advertiser. A seller account such as a Meta ad account or a Snap ad account only understands its own objects: a Meta dataset, a Snap Pixel, a TikTok pixel, a LinkedIn conversion rule, a Meta Custom Audience. A mapping tells Apostra which of those objects is the same thing as yours on that account. There are two kinds of object on a seller account:

Yours, once mapped. A pixel or list you map to one of your event sources or audiences works in every campaign that runs on that account.
Seller-managed or unmapped. Objects that belong to one storefront, such as a Meta Instant Forms leads source, or any object you leave unmapped, stay specific to that storefront. They pass through unchanged and are usable in that storefront’s own campaigns. Do not map your event sources to seller-managed objects.

The flow is always map, confirm, buy:

Map. Save the mapping with sellerAccounts on save_event_source or save_audience, or pick it on the Connections page.
Confirm. Apostra asks the seller account to confirm the object is there. The mapping reads pending, then synced, typically within a minute. An audience also reports the seller’s own size and match rate.
Buy. When a media buy’s optimization goal names your event source, Apostra sends the seller the mapped platform object instead of your id.

Apostra never creates a pixel or a dataset for you. Create it in the platform’s own console first, then map it. Saving a mapping reads what is on the account and records one id; it never changes anything on the platform.

Action needed if you name your own event sources in conversion goals. Map each event source on every seller account you buy on. A media buy whose goal names an event source with no mapping on that account fails before anything reaches the seller. Goals that carry a raw platform pixel id, buys with no event goal, and a Meta product’s explicit pixelId behave as before.

Find what is on each account

Open the Connections page for one connected account. It lists the pixels, datasets and audiences already there, and whether each is yours (Mapped to) or only on that storefront. See Open Media Partners. Over MCP, call open_connections_page with a connectionId and accountId:

{
  "name": "open_connections_page",
  "arguments": { "connectionId": "992", "accountId": "301" }
}

To read the same list as data, call get with the connection, its inventory and one account:

{
  "kind": "connection",
  "id": "992",
  "include": ["inventory"],
  "connectionAccountId": "301"
}

Each inventory item carries the platform’s own id as upstreamObjectId. That is the value you pass as sellerId when you map. The account id (here 301) is the accounts[].id from get({ "kind": "connection", "id": "992" }).

Map an event source

Save the event source with sellerAccounts. Each entry names the seller account and the id of the object on it:

{
  "advertiserId": "42",
  "idempotencyKey": "map-purchase-completed-2026-10-11-001",
  "eventSources": [
    {
      "eventSourceId": "purchase-completed",
      "name": "Purchase Completed",
      "eventTypes": ["purchase"],
      "actionSource": "website",
      "valueCurrencies": ["USD"],
      "sellerAccounts": [
        { "accountId": "301", "sellerId": "1234567890123456" }
      ]
    }
  ]
}

Saving asks the seller account to confirm the dataset straight away. Read the event source to see where it stands:

{
  "kind": "event_source",
  "id": "purchase-completed",
  "advertiserId": "42"
}

{
  "eventSourceId": "purchase-completed",
  "name": "Purchase Completed",
  "sellerAccounts": [
    {
      "accountId": "301",
      "storefront": { "id": "84", "name": "Meta" },
      "sellerId": "1234567890123456",
      "status": "synced",
      "lastSyncedAt": "2026-10-11T14:02:11.000Z",
      "health": null
    }
  ]
}

sellerId is null and status is pending until the seller account confirms the object. While the Conversion events switch is off for that storefront on the Connections page, the mapping stays pending with a SELLER_DATA_SHARING_NOT_PERMITTED blocker and nothing is checked. Turn the switch on and Apostra confirms the mapping within about an hour.

Event types must match

A destination that declares the event types it accepts must accept every type your source records. A LinkedIn conversion rule records one type, so it maps only to a source whose eventTypes are all on that rule’s list. A source with no eventTypes records every type, so it maps only to a destination that declares none. Meta, Snap and TikTok datasets and pixels accept all types. A mismatch is refused at save time with VALIDATION_ERROR on the entry’s sellerId. Narrow the source’s eventTypes, or map a destination that accepts them.

Use the source in a campaign goal

Name the event source in an event goal. Use your own event_source_id, not the platform’s id:

{
  "campaignId": "5501",
  "idempotencyKey": "campaign-5501-goal-2026-10-11-001",
  "optimizationGoals": [
    {
      "kind": "event",
      "event_sources": [
        {
          "event_source_id": "purchase-completed",
          "event_type": "purchase",
          "value_field": "order_total"
        }
      ],
      "attribution_window": { "post_click": { "interval": 7, "unit": "days" } },
      "priority": 1
    }
  ]
}

When a media buy on that account is created from this goal, the request Apostra sends the seller carries the mapped dataset id. Your media buy keeps showing your own event_source_id. Seller-managed sources and a platform’s built-in events are sent unchanged.

When a buy is refused

A media buy whose goal names an event source that cannot be used on that account fails before anything reaches the seller. A read of the media buy shows errorCode: "invalid_request", owned by you (buyer_input), and the failure reason starts with one of the codes below. Fix the cause, then create a new media buy.

Code	What it means	Fix
`SELLER_EVENT_SOURCE_DESTINATION_AMBIGUOUS`	The account has pixels or datasets, and you mapped none for this source	Map one: `sellerAccounts` on `save_event_source`, or Map on the Connections page
`SELLER_EVENT_SOURCE_DESTINATION_MISSING`	The account has none, or the one you named is not on the account, or does not accept every event type your source records	Create the pixel or dataset in the platform’s console and map it, or map one that accepts your source’s event types
`SELLER_DATA_SHARING_NOT_PERMITTED`	The Conversion events switch is off for this storefront	Turn on Conversion events for that storefront on the Connections page
`SELLER_OBJECT_TYPE_UNSUPPORTED`	This seller cannot take event sources, such as a managed seller agent	Optimize toward a metric instead, or buy from a seller account that can take event sources

A mapping that is still being confirmed is not a refusal: the buy is held and sent once the mapping reads synced. If a Meta product on the buy sets an explicit pixelId that differs from the dataset you mapped, the buy is refused for the conflict. Remove the explicit pixelId or map the same dataset. The full list of blocker codes and what each media-buy state does is in Measurement and incrementality.

Map an audience

Map an audience the same way. The audience must already exist: save its members first, then map it once it appears in the advertiser’s audience list: get({ "kind": "audience", "advertiserId": "42" }). An audience read takes the advertiser, not an audience id, and returns every audience for it, 50 per page (audienceOffset pages on).

{
  "advertiserId": "42",
  "audiences": [
    {
      "audienceId": "loyal-customers",
      "sellerAccounts": [
        { "accountId": "301", "sellerId": "23850000000012345" }
      ]
    }
  ]
}

An entry that only maps sends no members. Saving asks the seller account to confirm the audience is there. Read it back with the same listing, get({ "kind": "audience", "advertiserId": "42" }), and find the audience by audienceId; each of its sellerAccounts[] entries carries status, sellerId, and, once confirmed, the seller’s own size and match in match:

{
  "accountId": "301",
  "storefront": { "id": "84", "name": "Meta" },
  "sellerId": "23850000000012345",
  "status": "synced",
  "blocker": null,
  "lastSyncedAt": "2026-10-11T14:03:40.000Z",
  "match": {
    "matched_count": 48210,
    "effective_match_rate": 0.62
  }
}

match is null until the mapping is confirmed or when the seller reports nothing. If the audience is not on the account, or the seller reports it deleted, suspended or failed, the mapping reads SELLER_AUDIENCE_MISSING. Check the id on the Connections page and map the right audience.

Unmap

To end a mapping, send the account with unmap: true instead of a sellerId. This works the same on save_event_source and save_audience:

{
  "advertiserId": "42",
  "idempotencyKey": "unmap-purchase-completed-2026-10-11-002",
  "eventSources": [
    {
      "eventSourceId": "purchase-completed",
      "sellerAccounts": [{ "accountId": "301", "unmap": true }]
    }
  ]
}

Unmapping ends Apostra’s mapping on that account only. It never deletes or changes the pixel, dataset or audience on the platform. While a live media buy uses the mapping, the unmap fails with INVALID_STATE and names the media buys; unmap once they have ended or been canceled. A later media buy on that account that names the source fails as if it were never mapped.

Troubleshooting

What you see	Cause	Fix
Mapping stays `pending`	The seller account has not confirmed it yet, or the Conversion events switch is off for the storefront (`SELLER_DATA_SHARING_NOT_PERMITTED`)	Wait a minute and read again. If the blocker names the switch, turn on Conversion events on the Connections page
`VALIDATION_ERROR` on `sellerId` when saving	The destination’s declared event types do not cover every type your source records	Map a destination that accepts them, or narrow the source’s `eventTypes`
`REFERENCE_NOT_FOUND` when saving	The `accountId` is not an active connected account of yours, or the audience does not exist yet	Take `accountId` from `get({ "kind": "connection" })`; save the audience’s members first
`INVALID_STATE` when unmapping	A live media buy uses the mapping	Unmap after the media buys end or are canceled
Account shows `status: "failed"` with `SELLER_OBJECT_TYPE_UNSUPPORTED`	The seller cannot take event sources or audiences	Use a seller account that can, or optimize toward a metric
An account shows nothing to map	The account has not been read yet, or the seller does not list its objects	Each account is read about once an hour. If the seller will not list, enter the platform id by hand on the Connections page

Log events: send conversions to a registered event source.
Measurement and incrementality: how a source reaches each seller account and every refusal code.
Open Media Partners: the Connections page and its account inventory.
V3 tool reference: save_event_source, save_audience, and the connection inventory read.

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Help and updates

Use your event sources and audiences on each seller account

How it works

Find what is on each account

Map an event source

Event types must match

Use the source in a campaign goal

When a buy is refused

Map an audience

Unmap

Troubleshooting

​How it works

​Find what is on each account

​Map an event source

​Event types must match

​Use the source in a campaign goal

​When a buy is refused

​Map an audience

​Unmap

​Troubleshooting

​Related

How it works

Find what is on each account

Map an event source

Event types must match

Use the source in a campaign goal

When a buy is refused

Map an audience

Unmap

Troubleshooting

Related