instagram.media.count_max - letmepost.dev

What it checks

media.length <= 10. Carousels can mix images and videos (since IG Graph API v15).

Why 10

Meta’s Instagram Content Publishing API documents CAROUSEL containers at 2–10 children. Above that the create-container call returns an opaque code 100.

Failure response

{
  "error": {
    "code": "preflight_failed",
    "rule": "instagram.media.count_max",
    "platform": "instagram",
    "message": "Attached 12 media items; Instagram allows at most 10 per carousel.",
    "remediation": "Reduce to 10 items or fewer."
  }
}

Remediation

Trim to 10. If you have more, post the rest as a follow-up — IG doesn’t support carousel-of-carousels.

threads.media.count_max — Threads caps higher (20).