# 40161: Operation requires an identified client

Identifier: `identified_client_required`



The client had no established client ID, so an operation that requires one was refused.

## What you should do

Authenticate the client with a client ID, or relax the namespace setting that requires one. A client gets an identifier by connecting with a token issued for a specific client ID, making it an [identified client](https://ably.com/docs/auth/identified-clients.md). Alternatively, change the namespace's settings in your app so it no longer requires identified clients.

## Why it happens

An operation was attempted on a channel whose namespace requires identified clients, by a client that had no client ID. The `identified` namespace enforces this by default, and any namespace can be configured to.

## What you'll see

The error is reported with code 40161 and HTTP status 401. The message is typically `Access denied to channel: namespace <name> requires identified clients` or `operation not permitted as it requires an identified client`.