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

# Request Cancellation is stabilized

> Announcement that protocol-level request cancellation is now part of the stable ACP protocol.

**Published:** June 29, 2026

The [Request Cancellation RFD](/rfds/request-cancellation) has moved to Completed and the `$/cancel_request` notification is stabilized.

Either side can use the optional notification to request cancellation of an outstanding JSON-RPC request by ID. Implementations can return a valid partial result or the standard `-32800` Request Cancelled error, while feature-specific mechanisms such as `session/cancel` remain available for richer semantics.

For the protocol documentation, see [Cancellation](/protocol/v1/cancellation).