Meta Marketing API v26 migration: the agency checks

Your Meta Marketing API v26 migration can look complete while a campaign template still sends a retired placement. Graph API v20.0 was removed on September 24, and several changes reach older versions later in October. This review focuses on the requests your agency sends, the creative those requests attach, and the evidence you need before telling a client the work is finished.

Which migration dates belong on your calendar?

Start with the versions your tools actually call. Meta's July 29 release announcement gives a different schedule for individual removals and whole-version retirements. Treat October 27, 2026 as a deadline for the changes explicitly assigned to it.

The October 6 date comes from the Marketing API version table, which now lists v26.0 as the latest version.

Keep exceptions on the calendar separately. The v26.0 changelog leaves the all-version date for legacy New Pages Experience fields unconfirmed. It ties the constrained-audience requirement discussed below to v25.0 retirement for its eventual all-version application, with that date still TBD. Neither deserves an invented October 27 deadline.

Which ad requests need to change?

Give your integration owner the following checks from Meta's detailed v26.0 changelog. Match them against saved templates and request logs, including workflows your team uses only when launching a new client.

1. Remove Instagram Explore Feed from placement configurations sent through v26.0. Explicitly requesting it when creating or updating ad sets returns an error. Meta says delivery shifts to other eligible placements.
2. Remove story from messenger_positions in manual-placement requests. On v26.0, Meta silently strips it from effective placements; historical targeting can still contain it. Advantage+ Placements require no action for this deprecation, and Meta describes this as an API-only change that does not affect Ads Manager.
3. Check new ad sets in Housing, Employment, or Financial Products and Services campaigns. With constrained, non-broad targeting, explicitly set targeting_automation.advantage_audience to 1 or 0. Broad or default setups are unaffected; Meta's announcement also says existing-ad-set updates are unaffected.
4. For campaigns using Website and App conversion locations, stop attaching creatives with applink_treatment=web_only. This restriction affects ad creation and updates. Meta says the Ad Creative endpoint itself is unchanged, so a successful creative upload alone does not prove the ad can use it.

After a request succeeds, check effective placements. For Messenger Stories, success can accompany a changed configuration, and removing the only placement can still trigger normal placement validation errors. Save the result of the readback alongside the intended settings, rather than treating a clean job log as sufficient evidence. These distinctions are explicit in the release announcement.

What does your creative team need to review?

Search your creative templates for poll_spec and the poll type under interactive_components_spec. Meta's poll-ad deprecation blocks creating poll creatives or changing an ad to use one on v26.0, with all-version enforcement on October 27. Existing-ad updates that leave the creative unchanged can continue.

A hypothetical agency has a video whose final frame tells viewers to answer an attached poll. Removing the poll fields fixes only the request. Your creative lead should also inspect the video and approve a replacement ending if that instruction no longer makes sense.

There is another destination check beyond web_only. The v26.0 changelog's Shop Ads entry says eligible creatives default to destination_spec.destination_type = WEBSITE_AND_SHOP when the advertiser has a shop. It documents WEBSITE_AND_SHOP_OPT_OUT as the explicit opt-out value. Check the client's approved destination before your next creative is created.

For that same hypothetical video, approve the destination alongside the replacement ending. A landing-page-only approval does not establish that a shop destination is acceptable. Keep the approved creative and destination together in the handoff.

Which reporting and commerce dependencies can disappear?

Search code and report definitions for daily_outcomes_curve, budget_guardrail, and estimate_dau. Meta removes these Delivery Estimate response fields on v26.0 and across remaining supported versions on October 27, with no replacement API. Check account-level and ad-set-level delivery_estimate consumers, then identify any forecast or planning view that depends on them. Meta's field-removal details specify the scope.

Decide how your report handles missing values before the migration. A hypothetical client planning sheet might turn an absent estimate into zero through a default formula. Change that output to a clearly labeled unavailable value, and explain the removed estimate before the next review.

Keep this audit separate from Meta's click-through attribution change. A retired planning field and a changed attribution definition need different explanations; check the data source behind a disputed number before interpreting performance.

If your remit includes commerce integrations, inventory calls to Commerce Order Management as well. Meta's Graph API changelog lists 47 affected endpoints, already blocked on v26.0 and removed from remaining versions on October 27, with no replacement API. Identify any order, shipment, or refund dependency before promising continued access through the same integration.

How should your agency verify the migration?

Assign one owner to collect evidence from your developer, ad-operations lead, and each outside vendor. The useful question is which of your actual workflows was checked and what happened to its saved configuration.

1. Inventory the API versions, campaign templates, report consumers, and vendor-owned connections used for each account.
2. Review stored configuration, then compare it with current account state. A template-only review cannot establish what exists outside those templates. Practitioner coverage of the v26 audit is useful context for this inventory approach; use Meta's docs for the exact field rules.
3. Inspect shared request helpers for date_format and root GET /?ids=... calls, which now error on v26.0. Check caching assumptions too: Meta removes legacy ETag and 304 behavior. These Graph API protocol changes extend across supported versions on October 27.
4. Exercise affected create, update, and read paths in a controlled test setup. Keep test ads paused, inspect the resulting configuration, and confirm any missing fields are handled deliberately.
5. Keep a dated result for each affected workflow, including unresolved dependencies and who owns them. Recheck vendor status before the applicable deadline.

Before closing the work, require evidence from each workflow. A version number by itself does not show whether the creative, destination, or downstream report survived the change.

What should the client see in the handoff?

Give your client a short record of the affected workflow, approved change, and verification date. Label unresolved items plainly. Avoid claiming a performance improvement from this migration without account evidence.

For a hypothetical client using the poll-dependent video, the handoff would contain the revised ending, its approved destination, and confirmation that the resulting ad uses that configuration. Your account manager can review those items without reading an API request.

Keep placement experiments documented separately, including any work on Instagram Reels post-view ads. That gives your client a clear record of which changes were migration maintenance and which were deliberate media tests.

The review is complete when each affected workflow has an owner, a verified result, and an explanation the client can use. See Skayze's approach to paid media management.