preflight_failed

The request was syntactically valid but failed a platform-specific rule we check locally before the upstream call. This is the canonical “we caught it before the platform did” error.

What triggers it

Anything in the preflight rule catalog. A few high-frequency examples:

Bluesky post text > 300 graphemes (bluesky.text.max_graphemes)
Instagram post with no media (instagram.media.required)
Instagram media URL not publicly fetchable (instagram.media.reachable — the canonical OAuthException 2207052 translator)
Pinterest pin without a board id and no default board on the connected account (pinterest.board.required)

Response shape

preflight_failed.json

{
  "error": {
    "code": "preflight_failed",
    "message": "Post text is 312 graphemes; Bluesky allows at most 300.",
    "rule": "bluesky.text.max_graphemes",
    "platform": "bluesky",
    "remediation": "Shorten the post to 300 graphemes or fewer.",
    "docUrl": "https://docs.letmepost.dev/errors/preflight_failed",
    "ruleUrl": "https://docs.letmepost.dev/preflight/bluesky-text-max_graphemes",
    "requestId": "req_..."
  }
}

rule is always set on preflight_failed. The ruleUrl is the absolute link to that rule’s docs page — same path as /docs/preflight/<rule-with-dashes>/ — so a CLI can open it directly without parsing.

Why preflight matters

Without preflight you’d see this same constraint failure as an opaque platform response — a generic IG code 100, a LinkedIn 422 with no field path, a Threads HTTP 200 carrying a status code in the body. Preflight surfaces the rule id directly, with a remediation, before the upstream call ever happens.

Remediation

Open the rule’s page and follow the remediation. Every preflight rule has one.

Preflight — the full rule catalog.
platform_rejected — preflight passed but the platform still rejected. We treat this as a preflight gap and add a rule.

Errors

Preflight rules

What triggers it

Response shape

Why preflight matters

Remediation

​What triggers it

​Response shape

​Why preflight matters

​Remediation

​Related

What triggers it

Response shape

Why preflight matters

Remediation

Related