TIER_NOT_PURCHASABLE

That tier cannot be bought right now.

HTTP status	422
Group	Pricing and purchase
Retryable	No — sending it again changes nothing

What happened

It is draft, legacy, retired, or a custom tier you are not on the buyer list for.

What to do

Read GET /v1/pricing and pick a tier whose available is true.

The problem document

Every error is application/problem+json (RFC 9457) with the same shape:

{
  "type": "https://docs.co-relayer.com/errors/tier-not-purchasable",
  "title": "That tier cannot be bought right now.",
  "status": 422,
  "detail": "A sentence about this specific occurrence.",
  "instance": "req_01JB…",
  "code": "TIER_NOT_PURCHASABLE",
  "retryable": false,
  "hint": "Read `GET /v1/pricing` and pick a tier whose `available` is true."
}

See the error model for what each member means and how to handle unknown codes.