---
title: 1020: Mutually exclusive. | API Docs
description: Two fields were supplied where exactly one is allowed, or neither was.
---

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

The part or request declares a choice between fields and the request either set both or set none. Supply exactly one.

## Troubleshooting

- Inspect details\[].param and GET /v1/parts/{type} for which fields form the choice.

## Related

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