Meta Graph API: since October 27, 2026, requests with date_format or root GET /?ids= fail, pretty/debug and If-None-Match/ETag are ignored, and Commerce order endpoints are gone, even on pinned v21-v25. What changed and how do I fix my integration?

What it is: Meta's Graph API v26.0 changelog (released July 29, 2026) retired several legacy protocol behaviors for v26.0+, and applied the same change to all remaining supported Graph API versions beginning October 27, 2026. Pinning an older version (v21.0-v25.0) or making unversioned calls no longer avoids it. The same date removed the Commerce Order Management endpoints (orders, payments, refunds, shipments, returns) from all remaining versions, with no replacement API. Am I affected (search your code and HTTP client config for these): - date_format query parameter: requests now return a parameter error. - Root requests of the form GET /?ids=id1,id2: now return an error. - pretty=1 or debug=all: silently ignored; responses come back compact and without the __debug__ block, so code that read Meta's warnings from it gets nothing. - If-None-Match / ETag caching: ignored; you get full 200 responses instead of 304 Not Modified, so pollers use more bandwidth and rate-limit budget. - Anything calling Commerce order management (search for commerce_orders, order, refund, shipment endpoints): those calls now fail. Fix: 1. Remove date_format and parse the ISO-8601 timestamps Graph returns in your own code. 2. Replace GET /?ids= with individual object requests or a batch request (POST with a batch array of up to 50 relative GET requests). A batch returns a list of responses in request order, not an object keyed by ID, so update the parsing. 3. Drop pretty/debug; read errors and warnings from the normal error object and response headers instead. 4. Remove ETag/If-None-Match logic and resize pollers for full responses; poll less often or use webhooks where Meta offers them. 5. Commerce orders: Meta lists no replacement. Plan a business-side alternative for order sync; retries won't bring the endpoints back. 6. Upgrade your integration and Meta SDKs to target v26.0 (or later) so you test against the current behavior rather than relying on an old version. Verify: run your integration tests or replay typical calls against v26.0 and check for parameter errors; confirm pollers handle 200 responses with full bodies; confirm no code path still calls commerce order endpoints. Sources: https://developers.facebook.com/docs/graph-api/changelog/version26.0 https://developers.facebook.com/blog/post/2026/07/29/introducing-graph-api-v26-and-marketing-api-v26/ https://developers.facebook.com/docs/graph-api/batch-requests https://fixmation.dev/blog/meta-graph-api-27-october-all-versions