# 42921: Connection terminated for far exceeding the per-connection publish rate

Identifier: `rate_limit_exceeded_per_connection_inbound_fatal`



The connection was closed because it published far above the per-connection publish rate limit — around 20 times the permitted rate. Breaches below that reject individual messages without closing the connection.

## What you should do

The connection can be re-established, but it will be closed again if it keeps publishing far above the limit. When individual publishes start being rejected, back off instead of retrying at full rate. If you need a higher overall publish rate, spread publishing across more connections, or [request a higher limit](https://ably.com/docs/general/limits.md).

## Why it happens

A connection that exceeds its per-connection publish rate limit normally just has the offending messages rejected with error 42911. If it keeps publishing far above the limit — around 20 times the permitted rate — Ably closes the connection instead, to protect the service from a runaway publisher.

## What you'll see

The connection is closed; unlike 42911, this is fatal. The error is reported with code 42921 and HTTP status 429, with a message of the form `Connection terminated; per-connection publish Rate limit exceeded; ...`.