# 40331: Account not permitted in this cluster

Identifier: `account_not_permitted_in_cluster`



The request reached an Ably cluster the account is not permitted to use.

## What you should do

Configure every connecting client with the custom `endpoint` Ably issued for the account, following [platform customization](https://ably.com/docs/platform-customization.md). This routes requests to the account's dedicated cluster instead of a default global endpoint.

## Why it happens

The account is pinned to a dedicated cluster, and the request reached a different one than it is permitted to use. This normally happens when a client connects without the custom `endpoint` set, so it falls back to the canonical global endpoint `main.realtime.ably.net` rather than the account's dedicated endpoint such as `acme.realtime.ably.net`.

## What you'll see

The error is reported with code 40331 and HTTP status 403. The message is `Unable to activate account due to placement constraint (incompatible environment)`.