How to fix no_targets, invalid_type and missing_media in the MultiPost API

Fix these 400 responses by validating the payload before sending it: use text, image, videoor slideshow as the type, include at least one supported target, and supply the media field required by that type.

Treat the error code as a request-construction problem, not a transient network failure. Correct the payload deliberately instead of retrying the same JSON with exponential backoff.

Fetch GET /api/v1/accounts after the customer uses MultiPost accounts, persist an exact platform-and-handle target and construct the media field from the chosen post type on your server.

Confirm Pro or Agency through GET /api/v1/me and send the customer to plans and billing when API publishing is not enabled.

Text needs no media field, image uses imageUrl, video usesvideoUrl and slideshow uses imageUrls. The public API type is slideshow; the route maps it to the internal carousel format.

For URL-access failures after the shape is valid, switch to the guide on diagnosing media_unavailable rather than changing the request type.

MultiPost keeps only entries whose platform is a supported platform identifier. An array of misspelled or unsupported platform values is therefore empty after validation and returnsno_targets.

Build selections from the live accounts response and follow the guide to create a stable connected-account picker instead of accepting arbitrary platform text.

MultiPost returns a distinct code and message for unsupported types, missing targets and missing media, allowing your SaaS to point the user to the exact field that needs correction. Once validation passes, inspect per-target publish results as a separate execution stage.