Cause
No preview has been issued for the object: publishing, scheduling, opening or resuming require the digest of the latest one.
What to do
Request the preview (preview or launch-preview) and send its digest.
application/problem+json
{
"type": "https://masnet.com/developers/errors/preview_required",
"title": "Preview required",
"status": 409,
"detail": "...",
"code": "preview_required",
"correlation_id": "..."
}