---
title: 4001: Capability unknown | API Docs
description: Capability unknown
---

Capability unknown. This is an HTTP 409: the object’s current state conflicts with the request.

## Troubleshooting

- This is an operational or capability refusal, not a malformed request; the same call may succeed later.
- For a pause, honour `Retry-After`; for a capability refusal, send a part type the recipient’s device announced.