---
title: 1028: Unknown part type. | API Docs
description: The part's type names no member of the union.
---

**HTTP status:** `422`. May also be reported as a field-level finding in `error.details[]`.

The type at param is not one of the published part types. Nothing was sent.

## Troubleshooting

- GET /v1/openapi.yaml lists the part union; each member’s schema is at GET /v1/parts/{type}.

## Related

- [Part schemas](/channel/whatsapp/api/resources/contract/methods/part_schema/index.md)