# E01029 — UnknownQueryParameter

The request has a query parameter this endpoint does not accept.

- **HTTP status**: `422`
- **Type**: `validation_error`
- **Name**: `UnknownQueryParameter`

## What to do

Remove the parameter, or correct it to one this endpoint declares. Each rejected parameter appears in `details`, and an authenticated request also lists the names this endpoint accepts.

## Related

- [E01xxx — Infrastructure](/docs/api/errors/E01xxx): every code in this range
- [Errors](/docs/api/errors): the full wire contract, status mapping, and error catalog
- [Error handling](/docs/guides/errors): branching on `type` and `code`, validation details, and `vendor_code`