40331: Account not permitted in this 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. 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).