> ## Documentation Index
> Fetch the complete documentation index at: https://docs.permitcore.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Unknown cohort

> 400 — The `cohort` (per-manufacturer cohort) value is not recognized.

The `cohort` (per-manufacturer cohort) value is not recognized.

```json 400 application/problem+json theme={null}
{
  "type": "https://docs.permitcore.io/errors/unknown-cohort",
  "title": "Unknown cohort",
  "status": 400,
  "detail": "…",
  "instance": "/v1/permits/target",
  "request_id": "req_1f07fb45782b445e9f6312ba23921234"
}
```

Every PermitCore error is [RFC 9457](https://www.rfc-editor.org/rfc/rfc9457)
`application/problem+json`. **Branch on `type` (a stable URI)**, not on `title`
or `detail` (human-readable, may change).

## When it occurs

On `/v1/permits/target`, `cohort` is the per-manufacturer cohort filter (an A5 YAML basename such as `roofing-manufacturer`) — distinct from `target_segment`. An unknown basename returns this error.

## How to fix

Pass a recognized manufacturer-cohort basename, or use `target_segment` if you meant to filter by segment. See [GET /v1/permits](/api-reference/permits).

**Not retryable** — fix the request before resubmitting; retrying unchanged returns the same error.

See the full [error catalog](/errors) for the response shape and retry matrix.
Every response carries an `x-request-id` header — include it in any support request.